I'm stumped. My 851 Router is connected to AT&T with a PPPoE connection, and has run my home office for two problem-free years. I run a Vista Desktop (wired), a Vista laptop (wireless) and a Tivo (wireless) off of it.
A month ago, a housemate bought a new laptop which was unable to connect to the internet through the router whether wired or wireless, but works on other networks. (No MAC address filtering) In the meantime, the two PC's and the Tivo continued to work flawlessly with the 851.
Today I connected the housemate's laptop directly to AT&T PPPoE DSL (bypassing the router) and it worked fine. After I reconnected the 851 to AT&T, none of the computers hooked up to it will connect to the internet. Of course I did the obvious things like resetting modem and router. NOTHING else changed in the meantime that I can think of that would prevent the PC's from connecting to the router. Any suggestions? I am at wit's end.
Router SDL software says it's connected successfully to AT&T.
This is probably a really simple question compared to most stuff on here but I'm hoping someone can help.