How to Connect a DSL Modem With Two Routers to Create Two Wireless Networksby Steven Hill
Sometimes your home or office networking needs extend beyond the usual one modem, one router setup. For example, you may need to set up multiple independent wireless networks to connect devices in your home or office, but you have only one Internet connection provided by a single DSL modem. Fortunately, it is possible to connect two routers to the same DSL modem to create two wireless networks.
Decide which router you wish to use as your primary router. The primary router connects directly with the DSL modem. It should be the faster or better performing of the two routers. If the two routers are the same make and model, you can skip this step.
Connect an Ethernet cable to the Ethernet port on the modem, then connect the other end of this cable to the "WAN" port on your primary router.
Connect any Ethernet cable to the "WAN" port of your second router, then connect the other end of this Ethernet cable to an available "LAN" port on the first router.
Access the control panel of the first router. You can do this by temporarily connecting a computer via an Ethernet cable to one of the router's available "LAN" ports. Launch an Internet browser and type the IP address of the router, then press "Enter." This is normally 192.168.0.1, but it can vary by router. Check the device manual for the correct address. Locate the wireless setup section of your router's control panel. This differs between routers. Refer to your device manual if you have trouble finding it. Check what wireless channel the first router uses. Take note of the subnet mask used by the first router as well.
Access the control panel of the second router using the same method as the first. Navigate to the wireless setup section of that router. Set the wireless channel used by the second router a minimum of two away from that used by the first router. This ensures that the wireless networks created by each router don't interfere with one another.
Return to the primary menu of the second router. Check to make certain it doesn't use the same subnet mask as the first router. If it is using the same subnet mask, change it to a different one. The method for changing your subnet mask varies by router and you will have to refer to your device manual.
Disable DHCP service on the second router. Refer to your device manual to find the setting. This prevents further conflicts between the networks created by the two routers.