Ragnor: Do a tracert to your wow server and compare it to a tracert to a few of the wowtunnels ssh servers (eg: tunnel5.wowtunnels.com and tunnel2.wowtunnels.com) and compare the route taken see if you bypass the problematic AT&T router.
Ragnor that page is badly in need of an update.
I found a thread where people were posting their traceroutes to their realm IP's
They found it by running a netstat command and picking the IP adress which had ":3724" at the end (going through port 3724 ?)
Every traceroute I found listed a different IP to the one listed on that wow wiki page.