Having the same problems. I was playing fine around noon EST on Sunday, but after one of the patches I'm no longer able to login to any official server. After picking a server, it says "Joining Server x" in white text at the center of the screen for 20-30 seconds before getting the Connection Timeout error. I haven't had any luck at all getting into any official server for the past 14 hours, I've validated file integrity, reinstalled the game, and even reinstalled Steam with no luck. This is still an issue as of version 5.9.
If it helps, I AM able to connect to the unofficial servers just fine.