Myself and 3 friends attempted to play together this weekend during the stress test. Of the four of us, only one person was not having connection issues over and over. The 3 of us who were having a LOT of connection issues, (couldn't log in, couldn't get past character select when we could log in, getting booted when we finally did get in game,) were all either Time Warner cable or Comcast cable internet subscribers. We 3 got booted at exactly the same moment over and over.
The one person who had no connectivity issues at all was a Charter cable internet subscriber. Something to look into?