Though our servers still run v1.3 --- this is due to the fact that only a beta version of the linux dedicated server is available, and that on a closed admin list where I am not registered xD --- everyone should patch his/her UT3 to v2.0 and install the Titan pack after that to be able to connect to all servers. If not done so yet, you can go here and download:

Patch v2.0

Titan Pack

Let's hope a stable-like dedicated server of v2.0 will be available soon.