routers by keralaguest


									Page 1 of 15

Definition: Routers are physical devices that join multiple wired or wireless networks
together. Technically, a wired or wireless router is a Layer 3 gateway, meaning that the
wired/wireless router connects networks (as gateways do), and that the router operates at the
network layer of the OSI model.

Home networkers often use an Internet Protocol (IP) wired or wireless router, IP being the
most common OSI network layer protocol. An IP router such as a DSL or cable modem
broadband router joins the home's local area network (LAN) to the wide-area network (WAN)
of the Internet.

By maintaining configuration information in a piece of storage called the routing table, wired
or wireless routers also have the ability to filter traffic, either incoming or outgoing, based on
the IP addresses of senders and receivers. Some routers allow the home networker to update
the routing table from a Web browser interface. Broadband routers combine the functions of a
router with those of a network switch and a firewall in a single unit.

Definition: Wi-Fi is the industry name for wireless LAN (WLAN) communication technology
related to the IEEE 802.11 family of wireless networking standards. To some, the term Wi-Fi is
synonymous with 802.11b, as 802.11b was the first standard in that family to enjoy
widespread popularity. Today, however, Wi-Fi can refer to any of the established standards:
802.11a, 802.11b, 802.11g and 802.11n.

The Wi-Fi Alliance (see sidebar) certifies vendor products to ensure 802.11 products on the
market follow the various 802.11 specifications. Unfortunately, 802.11a technology is not
compatible with 802.11b/g/n, so Wi-Fi product lines have been somewhat fragmented.

Definition: Wireless access points (APs or WAPs) are specially configured nodes on wireless
local area networks (WLANs). Access points act as a central transmitter and receiver of WLAN
radio signals.

Access points used in home or small business networks are generally small, dedicated
hardware devices featuring a built-in network adapter, antenna, and radio transmitter. Access
points support Wi-Fi wireless communication standards.

Although very small WLANs can function without access points in so-called "ad hoc" or peer-
to-peer mode, access points support "infrastructure" mode. This mode bridges WLANs with a
wired Ethernet LAN and also scales the network to support more clients. Older and base model
access points allowed a maximum of only 10 or 20 clients; many newer access points support
up to 255 clients.

Linksys WAP54G Wireless Access Point

Also Known As: base station
A wireless access point (sometimes called an "AP" or "WAP") serves to join or "bridge" wireless
clients to a wired Ethernet network. Access points centralize all WiFi clients on a local network
in so-called "infrastructure" mode. An access point in turn may connect to another access
point, or to a wired Ethernet router.

Wireless access points are commonly used in large office buildings to create one wireless local
area network (WLAN) that spans a large area. Each access point typically supports up to 255
client computers. By connecting access points to each other, local networks having thousands
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of access points can be created. Client computers may move or "roam" between each of these
access points as needed.

In home networking, wireless access points can be used to extend an existing home network
based on a wired broadband router. The access point connects to the broadband router,
allowing wireless clients to join the home network without needing to rewire or re-configure
the Ethernet connections.

As illustrated by the Linksys WAP54G (compare prices) shown above, wireless access points
appear physically similar to wireless routers. Wireless routers actually contain a wireless
access point as part of their overall package. Like wireless routers, access points are available
with support for 802.11a, 802.11b, 802.11g or combinations.

The centerpiece product of many home computer networks is a wireless router. These routers
support all home computers configured with wireless network adapters (see below). They also
contain a network switch to allow some computers to be connected with Ethernet cables.

Wireless routers allow cable modem and DSL Internet connections to be shared. Additionally,
many wireless router products include a built-in firewall that protects the home network from

Illustrated above is the Linksys WRT54G (compare prices). This is a popular wireless router
product based on the 802.11g Wi-Fi network standard. Wireless routers are small box-like
devices generally less than 12 inches (0.3 m) in length, with LED lights on the front and with
connection ports on the sides or back. Some wireless routers like the WRT54G feature external
antennas that protrude from the top of the device; others contain built-in antennas.

Wireless router products differ in the network protocols they support (802.11g, 802.11a,
802.11b or a combination), in the number of wired device connections they support, in the
security options they support, and in many other smaller ways. Generally only one wireless
router is required to network an entire household.

Linksys WRT54G Wireless Broadband Router
A wireless network adapter allows a computing device to join a wireless LAN. Wireless network
adapters contain a built-in radio transmitter and receiver. Each adapter supports one or more
of the 802.11a, 802.11b, or 802.11g Wi-Fi standards.

Wireless network adapters also exist in several different form factors. Traditional PCI wireless
adapters are add-in cards designed for installation inside a desktop computer having a PCI
bus. USB wireless adapters connect to the external USB port of a computer. Finally, so-called
PC Card or PCMCIA wireless adapters insert into a narrow open bay on a notebook computer.

One example of a PC Card wireless adapter, the Linksys WPC54G (compare prices) is shown
above. Each type of wireless network adapter is small, generally less than 6 inches (0.15 m)
long. Each provides equivalent wireless capability according to the Wi-Fi standard it supports.

Some notebook computers are now manufactured with bulit-in wireless networking. Small
chips inside the computer provide the equivalent functions of a network adapter. These
computers obviously do not require separate installation of a separate wireless network
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Linksys WPC54G Wireless Network Adapter

How to build a wireless home network:

What is a WLAN?

We've already said that a WLAN is a "typical" wireless home network. That's because a WLAN
is a wireless LAN, and a LAN is a related group of networked computers situated in close
physical proximity to each other

What is Wi-Fi?

Wi-Fi is an industry name used to market wireless networking products. You'll find a black-
and-white Wi-Fi logo or certification emblem on virtually any new wireless equipment you buy.
Technically speaking, Wi-Fi signifies conformance to the 802.11 family of wireless
communication standards (described below). But because all mainstream wireless home
network gear uses the 802.11 standards today, basically the term "Wi-Fi" merely distinguishes
wireless equipment from other network gear.

What is 802.11a/802.11b/802.11g?

802.11a, 802.11b, and 802.11g represent three popular wireless communication standards.
Wireless networks can be built using any of the three, but 802.11a is less compatible with the
others and tends to be a more expensive option implemented only by larger businesses. Use
the supplemental article below to help you pick 802.11 standard(s) for your wireless LAN.

WEP is an important feature of wireless networks designed to improve security. WEP
scrambles (technically speaking, encrypts) network traffic mathematically so that other
computers can understand it, but humans cannot read it. WEP helps protect your WLAN from
wardrivers and nosy neighbors, and today, all popular wireless equipment supports it. Because
WEP is a feature that can be turned "on" or "off," you'll simply need to ensure it is configured
properly when setting up your network.
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Next - Types of Wireless Equipment

The five types of equipment found in wireless home networks are:

       wireless network adapters
       wireless access points
       wireless routers
       add-on wireless antennas
       wireless signal boosters

Some of this equipment is optional depending on your home network configuration. Let's
examine each piece in turn.

The building blocks of a wireless LAN are network adapters, access points, wireless
routers, add-on wireless antennas and signal boosters. Of these, only network adapters
are truly required to build a wireless home network. However, many wireless LANs also utilize
some of the other equipment, as explained below.

WLAN Layout with Wireless Access Point

Wireless Network Adapters

Each computer you wish to connect to a WLAN must possess a wireless network adapter.
Wireless adapters are sometimes also called NICs, short for Network Interface Cards. Wireless
adapters for desktop computers are often small PCI cards or sometimes card-like USB
adapters. Wireless adapters for notebook computers resemble a thick credit card (see Page 1
sidebar for illustration). Nowadays, though, an increasing number of wireless adapters are not
cards but rather small chips embedded inside notebook or handheld computers.

Wireless network adapters contain a radio transmitter and receiver (transceiver). Wireless
transceivers send and receive messages, translating, formatting, and generally organizing the
flow of information between the computer and the network. Determining how many wireless
network adapters you need to buy is the first critical step in building your home network.
Check the technical specifications of your computers if you're unsure whether they contain
built-in wireless adapter chips.

Wireless Access Points
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A wireless access point serves as the central WLAN communication station. In fact, they are
sometimes called "base stations." Access points are thin, lightweight boxes with a series of
LED lights on the face (see Page 1 sidebar for illustration).

Access points join a wireless LAN to a pre-existing wired Ethernet network. Home networkers
typically install an access point when they already own a broadband router and want to add
wireless computers to their current setup. You must use either an access point or a wireless
router (described below) to implement "hybrid" wired/wireless home networking. Otherwise,
you probably don't need an access point.

Many access point products are available on the market; see the following supplementary
article for some good examples:

Wireless Routers

A wireless router is a wireless access point with several other useful functions added. Like
wired broadband routers, wireless routers also support Internet connection sharing and
include firewall technology for improved network security. Wireless routers closely resemble
access points (see Page 1 sidebar for illustration).

A key benefit of both wireless routers and access points is scalability. Their strong built-in
transceivers are designed to spread a wireless signal throughout the home. A home WLAN
with a router or access point can better reach corner rooms and backyards, for example, than
one without. Likewise, home wireless networks with a router or access point support many
more computers than those without one. As we'll explain in more detail later, if your wireless
LAN design includes a router or access point, you must run all network adapters in so-called
infrastructure mode; otherwise they must run in ad-hoc mode.

Wireless routers are a good choice for those building their first home network. See the
following article for good examples of wireless router products for home networks:

Next - WLAN Configurations

Now that you have a good understanding of the pieces of a wireless LAN, we're ready to set
them up according to your needs. Don't worry if you haven't settled on a configuration yet; we
will cover all of them.

Ad Hoc Wireless LAN Layout
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To maximize benefit from the directions below, have your answers ready for the following

        do you want to extend your wired home network with a WLAN, or are you building a
    completely new network?
        how many wireless computers do you plan to network, and where in the home will be
    they be located?
        what operating systems do/will you run on your networked computers?
        do you need to share your Internet connection among the wireless computers? how
    else will you use this WLAN? file sharing? network gaming?

Installing a Wireless Router

One wireless router supports one WLAN. Use a wireless router on your network if:

       you are building your first home network, or
       you want to re-build your home network to be all-wireless, or
       you want to keep your WLAN installation as simple as possible

Try to install your wireless router in a central location within the home. The way Wi-Fi
networking works, computers closer to the router (generally in the same room or in "line of
sight") realize better network speed than computers further away.

Connect the wireless router to a power outlet and optionally to a source of Internet
connectivity. All wireless routers support broadband modems, and some support phone line
connections to dial-up Internet service. If you need dial-up support, be sure to purchase a
router having an RS-232 serial port. Finally, because wireless routers contain a built-in
access point, you're also free to connect a wired router, switch, or hub. (See diagram Page 2

Next, choose your network name. In Wi-Fi networking, the network name is often called the
SSID. Your router and all computers on the WLAN must share the same SSID. Although your
router shipped with a default name set by the manufacturer, it's best to change it for security
reasons. Consult product documentation to find the network name for your particular wireless
router, and follow this general advice for setting your SSID.

Last, follow the router documentation to enable WEP security, turn on firewall features, and
set any other recommended parameters.

Installing a Wireless Access Point

One wireless access point supports one WLAN. Use a wireless access point on your home
network if:

      you don't need the extra features a wireless router provides AND
      you are extending an existing wired Ethernet home network, or
      you have (or plan to have) four or more wireless computers scattered throughout the

Install your access point in a central location, if possible. Connect power and a dial-up Internet
connection, if desired. Also cable the access point to your LAN router, switch or hub. See the
diagram in the Page 3 sidebar for details.
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You won't have a firewall to configure, of course, but you still must set a network name and
enable WEP on your access point at this stage.

Configuring the Wireless Adapters

Configure your adapters after setting up the wireless router or access point (if you have one).
Insert the adapters into your computers as explained in your product documentation. Wi-Fi
adapters require TCP/IP be installed on the host computer.

Manufacturers each provide configuration utilities for their adapters. On the Windows
operating system, for example, adapters generally have their own graphic user interface (GUI)
accessible from the Start Menu or taskbar after the hardware is installed. Here's where you set
the network name (SSID) and turn on WEP. You can also set a few other parameters as
described in the next section. Remember, all of your wireless adapters must use the same
parameter settings for your WLAN to function properly.

Configuring an Ad-Hoc Home WLAN

Every Wi-Fi adapter requires you to choose between infrastructure mode (called "access point"
mode in some configuration tools) and ad-hoc ("peer to peer") mode. When using a wireless
access point or router, set every wireless adapter for infrastructure mode. In this mode,
wireless adapters automatically detect and set their WLAN channel number to match the
access point (router).

Alternatively, set all wireless adapters to use ad hoc mode. When you enable this mode, you'll
see a separate setting for channel number. All adapters on your ad hoc wireless LAN need
matching channel numbers.
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Ad-hoc home WLAN configurations work fine in homes with only a few computers situated
fairly close to each other. You can also use this configuration as a fallback option if your
access point or router breaks:

See also : Ad Hoc Wi-Fi Home Network Diagram

Configuring Software Internet Connection Sharing

As shown in the diagram, you can share an Internet connection across an ad hoc wireless
network. To do this, designate one of your computers as the host (effectively a substitute for a
router). That computer will keep the modem connection and must obviously be powered on
whenever the network is in use. Microsoft Windows offers a feature called Internet Connection
Sharing (ICS) that works with ad hoc WLANs.

Next > WLAN Tips and Tricks

Definition: An SSID is the name of a wireless local area network (WLAN). All wireless devices
on a WLAN must employ the same SSID in order to communicate with each other.

The SSID on wireless clients can be set either manually, by entering the SSID into the client
network settings, or automatically, by leaving the SSID unspecified or blank. A network
administrator often uses a public SSID, that is set on the access point and broadcast to all
wireless devices in range. Some newer wireless access points disable the automatic SSID
broadcast feature in an attempt to improve network security.

SSIDs are case sensitive text strings. The SSID is a sequence of alphanumeric characters
(letters or numbers). SSIDs have a maximum length of 32 characters.

What Is a Network Name?
Answer: A network name is a text string that devices use to reference a particular computer
network. These strings are, strictly speaking, separate from the names of individual devices
and the addresses they use to identify each other. Several different forms of network naming


Wi-Fi networks support a type of network name called SSID. Wi-Fi access points and clients
are each always assigned an SSID to help identify each other. When a person speaks of
wireless network names, they typically are referring to SSIDs.

Wireless Routers / Access Point Interference within the Home

When installing an 802.11b or 802.11g access point or router, beware of signal interference
from other home appliances. In particular, do not install the unit within 3-10 feet (about 1-3
m) from a microwave oven. Other common sources of wireless interference are 2.4 GHz
cordless phones, baby monitors, garage door openers, and some home automation devices.

If you live in a home with brick or plaster walls, or one with metal framing, you're may
encounter difficulty maintaining a strong WLAN signal. Wi-Fi is designed to support signal
range up to 300 feet (about 100 m), but barriers reduce this range substantially. All 802.11
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communications (802.11a most of all) are affected by obstructions; keep this in mind when
installing your access point.

      Range of Wi-Fi LANs

Wireless Routers / Access Point Interference from Outside

In densely populated areas, it's not uncommon for wireless signals from one person's home
network to penetrate a neighboring home and interfere with their WLAN. This happens when
both households set conflicting communication channels. Fortunately, when configuring an
802.11b or 802.11g access point or router, you can (except in a few locales) change the
channel number employed.

In the United States, for example, you may choose any WLAN channel number between 1 and
11. If you encounter interference from neighbors, you should coordinate channel settings with
them. Simply using different channel numbers won't always solve the problem. However, if
both parties use a different one of the channel numbers 1, 6 or 11, that will guarantee
elimination of cross-WLAN interference.

      Change the Wi-Fi Channel Number to Avoid Interference

MAC Address Filtering

Newer wireless routers and access points support a handy security feature called MAC address
filtering. I wholeheartedly recommend it. This feature allows you to register wireless adapters
with your access point (or router), and force the unit to reject communications from any
wireless device that isn't on your list. MAC address filtering combined with WEP encryption
affords very good security protection.

      Tip - Enable MAC Address Filtering

Wireless Adapter Profiles

Many wireless adapters support a feature called profiles that allows you to set up and save
multiple WLAN configurations. For example, you can create an ad hoc configuration for your
home WLAN and an infrastructure mode configuration for your office, then switch between the
two profiles as needed. I recommend setting up profiles on any computers you plan to move
between your home network and some other WLAN; the time you spend now will save much
more time and aggravation later.

WEP Encryption

Among the options you'll see for activating wireless encryption, 128-bit WEP is a safe bet.
Older 40 or 64-bit WEP offers inadequate protection. A few 802.11g products support 152-bit
or 256-bit WEP, that is fine too, if all of your gear supports it. Newer equipment offers WPA.
General-purpose WPA is unnecessarily complex for a home WLAN, but WPA-PSK works well.

To set 128-bit WEP, pick and assign a number called a WEP passkey. You must apply the
same WEP settings and passkey to the access point (router) and all adapters.
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General Tips

If you've finished installing the components, but your home network isn't functioning correctly,
troubleshoot methodically:

        Can't reach the Internet? Temporarily turn off your firewall to determine whether you
    have a firewall configuration problem, or some other issue.
        Likewise, turn on and test your wireless adapters one by one, to determine if problems
    are isolated to a single computer or common to all.
        Try ad hoc networking if infrastructure networking isn't functional, and perhaps you'll
    identify a problem with your access point or router.
        To help you work methodically, as you build your network, write down on paper the
    key settings like network name, WEP passkey, MAC addresses, and channel numbers (then
    eat the evidence afterward!).
        Don't worry about making mistakes; you can go back and alter any of your WLAN
    settings any time.

Finally, don't be surprised if your wireless LAN performance doesn't match the numbers
quoted by the manufacturer. For example, although 802.11b equipment technically supports
11 Mbps bandwidth, that is a theoretical maximum never achieved in practice. A significant
amount of Wi-Fi network bandwidth is consumed by overhead that you cannot control. Expect
to see more than about one-half the maximum bandwidth (5.5 Mbps at most for 802.11b,
about 20 Mbps at most for the others) on your home WLAN.


Armed with the information contained in this tutorial, you're now well on your way to building
a working home WLAN. Welcome to the world of wireless networking!

Enable or disable a network adapter
You need a network adapter to connect a computer to a network. You can disconnect
your computer from a network by disabling your network adapter, and you can
sometimes solve connection problems by disabling and then re-enabling the adapter.

Start->Control Panel->Network and Internet-> Network and Sharing Center-> Manage
Network Connections

    1. Open Network Connections by clicking the Start button, clicking Control Panel,
       clicking Network and Internet, clicking Network and Sharing Center, and then
       clicking Manage network connections.
    2. Right-click the network adapter, and then do one of the following:
           o To disable the network adapter, click Disable. If you are prompted for an
               administrator password or confirmation, type the password or provide
           o To enable the network adapter, click Enable. If you are prompted for an
               administrator password or confirmation, type the password or provide
    Page 11 of 15

           If you disable the adapter, you have to enable it again to connect to a network.


    Your computer might have more than one network

          Another possible reason why you might not see all devices under Windows Vista could
      be because the Link Layer Topology Discovery (LLTD) protocol is disabled on the network
      adapter, or is not supported by the network adapter itself (a very likely culprit).

          router for instructions about setting the wireless signal channel.

     Windows is not configured to connect to the right type of network.

    Check the information that came with the router or access point to find out what
    connection mode the device is set to. The mode should be either ad hoc (when devices
    communicate directly without going through a router or access point) or infrastructure
    (when devices communicate by going through a router or access point). Make sure the
    setting in Windows for this network matches the setting on the device. To check this,
    follow these steps:

       1. Open the Command Prompt window by clicking the Start button , clicking All
          Programs, clicking Accessories, and then clicking Command Prompt.
       2. Type netsh wlan add filter networktype=network type.

    The network you are looking for is set to not broadcast its network name

    Wireless routers and access points can be set up so that they don't broadcast the network
    name. In this case, you can't detect that the network is in range (in order to connect to it)
    unless you have previously connected to the network or you manually connect to the
    network using the service set identifier (SSID). To connect to a network that is not
    broadcasting, follow these steps:

       1. Open Connect to a Network by clicking the Start button , and then clicking
          Connect to.
       2. Click Set up a connection or network.
       3. Click Manually connect to a wireless network, and then type the network
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         The network will be added to your list of networks and will be available to
         connect to in the future when your computer is in range of the network.

 The wireless network adapter is in monitor mode.

 If a network monitoring program is running on your computer, the wireless network
 adapter will be set to monitor mode, which prevents Windows from connecting to
 wireless networks. To connect to a wireless network, close the network monitoring
 program or follow the instructions in the program to exit monitor mode.

 Check workgroup setting

 Local access only - NO internet acces on Vista Ultimate

 It took me 4 hours to resolve this problem with my sprint broadband card. The
 problem turned out to be with the workgroup setting in the system settings. When I
 installed vista I chose a workgroup. So, when I tried to connect to the internet it was
 looking for that workgroup (resulting in 'local only' status). So to resolve the problem
 I went to my system settings and removed the workgroup and chose that this
 computer was for home use and not office network. When I rebooted the system I
 immediately noticed the internet icon in the windows toolbar.

 Hope this helps all of you who have had this same problem.

 Good Luck.

 Disable disable IP6 options in both network adapters (wireless and ethernet)
 Via network connections

 Unidentified Network & Local Access Only in
 Windows Vista & 7
 I have seen this several times in Vista, even in Windows 7. You try to connect to the LAN or Wifi and you
 are never prompted to choose a network location (Home, Work or Public). When this happens The
 Network and Sharing Center will X out the Internet icon and show Local Access Only. The problem is,
 there is no way to choose which location you want! Lame.

 So, do this…

1.       In the Network & Sharing Center, click the “Change adapter settings” link at the left.
2.       Open the properties of the adapter in you are trying to use.
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3.        Un-check the Link-Layer Topology Discovery items. There are two, Mapper and Responder.
4.        Click OK

 From here, you should be connected automatically if not prompted for the Network Location. If no such
 luck, then you can also try disabling IPv6. I usually do anyway, so I don’t know for sure if it is necessary.

 Another solution I have found that may work is to run the following from a command prompt: route
 delete This seemed to work for me once, but it had no effect the last time I tried. The reason it
 may work is that Windows creates a primary default gateway of to block internet access until you
 choose the Network Location. By removing that route and restoring the correct gateway, it may just get

 I'm running Windows 7 64 on a Lenovo w500 and I saw the same exact issue. I was
 able to fix it by changing the encryption on my wireless router. It looks to me like
 Windows 7 does not support 64bit encryption, only No encryption or 128bit or

 I browsed to my router's home page and changed the encryption to be unsecured,
 and then I was able to connect. I then changed it to 128bit and was able to connect
 as well.

 If that doesn't work for you, you may want to try all the other things I tried that
 didn't work for me :-)

 1.   Uninstall the wireless driver, reboot and allow the Lenovo to reinstall the driver.
 2.   Go to the properties for your connection and disable IPv6, reboot.
 3.   Shut down the wireless router for 15 seconds.
 4.   ipconfig /reset
 5.   scream at the computer to knock it off


 Re: Windows Vista wireless internet "Local Access Only"

 Cards go bad the most obnoxious reasons. Is it an external antenna or is it a base you set
 on top of your computer?

  Plug Necessary Cords In
         Turn off your modem (unplugging it is the best way) and then plug one end of the
          network cable that was bundled with your router into your modem. You may need to
          squeeze a small hinge to click it into place. Then plug the other end of the same
          cable into the Internet port on your wireless router. See your manual for port
Page 14 of 15

Test the Router
      Turn your modem back on by plugging it in. Wait for the lights to flash. A source light
       as well as a broadcast light should flash. Your manual should have an illustration that
       details what a properly functioning light scheme should look like. Once you have
       confirmed that everything is working fine, unplug the cable from the router (not the
       modem) and then plug it directly into your computer's Ethernet port.

Configure the Router
      Open your Internet browser and type the router's setup address as detailed in your
       manual and type in the address to configure your router. See the resource section for
       a link to a PDF file that has the addresses (as well as admin names and passwords)
       for most common routers. Once you have entered your router's set-up utility, follow
       the prompts to set security settings as well as other preferences. Then unplug the
       Ethernet cable from your computer and plug it back into the router. Your wireless
       network is now set up.

Read more: Setting Up a Wireless Router With a Cable Modem |

Did you try flushing the IP? ipconfig /release and ipconfig /renew

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