Advice, log into UT3 before respawn before coming. Then at respawn, stay in offline mode. I've seen their servers reject legit keys at LANs. I believe this to be something about more than 8 players having the same IP, but I could be wrong.
2.1 is the latest patch (UT3Patch5.exe). If your game isn't patched up, don't worry as I have all patches available. Also, if you have an NVidia card, make sure you have the latest drivers with the latest PhysX.