I wanted to share a SBC Yahoo connection by connecting a router to the modem. The modem currently has NAT, DHCP enabled. It is on a 172.xxx.xxx.xxx network. The router can be accessed at 192.168.0.1. All the physical connections I am sure is correct. But internet does not work. Do I need to disable NAT on the modem and/or make sure the router and the modem are on the same subnet? Any advice will be greatly appreciated.

I'm assuming you have the dsl modem connected to the router. Did you run the router config to setup the dsl service? Because it's dsl, it requires authentication via ppoe. You need to set that up in the router, and then the router does all the connecting for you. Also, run ipconfig from the cmd prompt and make sure it recognizes your router as your default gateway, and that your ip address is in the 192.168.0.x scope. If your ip is something like 169.172.... then your system isn't obtaining an ip via dhcp, and you need to find out why. You do not want to disable nat on the router, as that will make your systems more easily accessible to hack attempts. Check the router config and make sure sbc's settings are in there, including your user id (youremail@whateverdomain.xxx) and make sure it's set to ppoe and that your password is stored in there as well.

Thank you for your reply. Sorry, it is actually Earthlink not SBC. The modem is connected to the wan port of the router. Authentication info has been set up correctly. Both the modem and modem NAT and DHCP. I can get an ip the router when the router is connected, or the modem when the PC is connected directly to the modem. I do have Covad dsl at home so I know basic router configuration. But this Earthlink dsl stumps me.

Typo. I meant both modem and router have NAT and dhcp.

ok, so you've got two devices providing dhcp. I would try to configure the modem to disable both nat and dhcp if you can, and see if that makes a difference. I didn't understand before when you said the modem also provided nat and dhcp.