Airport will not connect to the internet

[eric2006]

I am trying to fix an Airport for a friend. It's a Dual Ethernet/Snow Airport Base Station. It works perfectly for P2P connections, but I cannot get it to connect to the internet. I've tried:
Unplugging the Modem
Unplugging the Airport
Soft-reset of the Airport
Hard-reset of the Airport
Changing cables
Changing ports
Disabling Distribute IP address
Updating the AirPort
Airport Setup Assistant
Using Airport Admin Utility
Nearly every Apple Support Article

At their house, it was connected directly to the modem, and it would not work. Here, it's coming off of the router. What it's connecting to doesn't seem to be the problem. It just won't share whatever it's connecting to. I've tried connecting with 3 different Macs, two 10.4.7 and one 10.2.8. I'm starting to think something is broken with it. Any suggestions?

It's not showing up in the DHCP client table of the router..

 

[jh2112]

Have you tried manually inputting your isp's dns server addresses? P2P makes direct connections. The 'internet' requires name resolution, so it could be this.

 

[eric2006]

I've tried that. Right now, the Airport is just acting as a bridge on my network. By P2P, I mean computers on the Airport network can talk to each other.

 

[eric2006]

I had a chance to bring it in to the Genius bar today. My worst fear was that after everything I had tried, it would work at the store. It did. ("Are you sure you plugged it into the port with the circle?") Luckily, it died after about 2 minutes, which apparently was what it had been doing. So the Genius worked on it. And worked on it. After my 8 hours of troubleshooting, it was almost worth it to see a Genius stumped. A half hour later, he decided that the Airport was toast, as I had suspected. It would cost him $300 to order a replacement, so he said to just get a new Airport. The new Airports are not cheap. We ended up getting a Linksys WRT54G for 50 bucks, and I set that up in a few minutes. I got a cool-looking broken Airport out of the deal, though, which will look awesome, even if it doesn't work.