Today the masterserver was down....
In this situation we were not even able to setup local lan games! You can open a server ( without publishing ) and then others can try to connect via find lan games. They find the server and are shown there for some seconds, but without successful connect!
Same happens to others on the internet if you give them your IP adress.
Somehow the masterserver must be used too often ...
UPDATE:
OK, playing is possible, but once you publish the game / or you maybe had any kind of masterserver communication, connecting is impossible.
Update2:
I think the problem is, that the communication with the masterserver(who is down ) gets stucked and by this all other communication is handled the right way. This is why the clients get dropped.