My partner and I have both pre-ordered the game and have had a horrible time trying to connect to each other or other people for multiplayer games. This could be very obvious or not but we have noticed that if we both start the game afresh from desktop and go to skirmish room, one of us hosts and it will state:
Port= 6073. The other can join every time without fail. We play our game have lotsa fun yeah! THEN the next time we try to host a game, either one of us it will say Port=0. Nothing we do can change this even taking off auto port and typing in 6073. If we then restart the game as before we will get Port 6073 and the connection will work.
Hope this helps a little with the netcode issues 