There is a conflict between the Linksys router and the AT&T - they both share the same network address
, so when they are connected together, they don't cooperate.
You can change the address of the Linksys and everything will work. Here are the steps to do this, including wireless security. During the setup, only the router and a computer will be connected together - not the modem:
Power off the modem and pc. Connect the pc with an ethernet cable to one of the 4 ethernet ports on the back of the router. The modem should not be connected at this point. Disconnect it if it is currently connected.
With power still on to the router, press and hold the reset button on the back of the router with a pen for 15 seconds, then release. Power off the router.
Wait one minute, then power on the router. Wait one more and power on the pc. Open Internet Explorer and enter this address:
A login screen will appear - use this login:
(There is no username - leave it blank.)
You should now be inside the setup of the router.
Click Wireless - change the network name (SSID) to something different - this will be the name of your network. Save the settings at the bottom of the page.
Click Wireless Security, just below Wireless. Change the security mode to WPA2-Personal. A box labeled pre-shared key/passphrase will appear - this is your wireless password. Enter anything you would like, just make sure it is at least 8 characters in length. Save the settings.
Now, the important part - click the Setup tab - find the Local IP Address and change it from 192.168.1.1 to 192.168.5.1. Save the settings and power off the pc and router.
Reconnect the modem to the ethernet port of the router, then power it on - wait 60 seconds.
Power on the router - wait 60 seconds
Power on the pc
Everything should work together at this point. If you have any wireless devices, connect to the network name you made, then enter the password XXXXX prompted.
If you aren't quite sure about the wireless connection, let me know what devices you would like to connect and I can provide instructions.
Edited by Kevin on 6/21/2010 at 5:46 PM EST