I can access the www.att.net site, but when I try to log in - to see my customized home page there or to access my mail on their server - I get a timeout from "loginprodx.att.net". Everything else in Firefox seems to be working.
I can access the login screen (and my homepage/email) on att.net from Internet Explorer.
I have tried clearing the Firefox cache and "forgetting" about att.net, but it does not fix the problem.
(Normally I use Thunderbird to access my e-mail, and that is working. But every once in a while I want to use web access to check my spam folder in case something useful got diverted to it.)
Oddly enough, the problem went away on its own. Today I can log in. I did not take any action (other than shutting down my computer at night and rebooting in the morning each day and whenever thunderstorms were very near.)