Me and my wife have been having almost exactly the same issue. For us it started the day before the patch though so I can't blame the patch for it really. Today I'm logged in fine but my wife's character constantly disconnects, at other times it affects both of us.

I have also noticed that messing with the game config in some way can fix the problem. This doesn't always work.

I've contacted our ISP (also Virgin Media) who say that they can see no problems with our connection.

After reading your post about logging into other characters we tried it, and what do you know.. the connection is fine on the new character.

Seems to be something strange going on server side?