OK, it wasn't AT&T's site
OK, after taking about things a little more, I decided my Linksys might be at fault. It was after all about four years old (not that old I understand) but we had also had a power fluctuation the night before (yes, I had it plugged into a surge protector). I tried a few more tests and found I was having a few other problems such as the Linksys not maintaining a PPOE connection to my ISP. I picked up a new Linksys and everything seems resolved. I did try the other standard stuff like applying the latest firmware for the old Linksys, but no go. Anyway, apologies to AT&T.