i had a lot of problems with the multiplayer. I was getting DC's all the time.
I googled the problem and saw that a lot of people are having this problem.
I just got a new router: Netgear WNDR3700 with firmware V1.0.6.98
Apperently this version is full of bugs (source: netgear) and has known DC issues with a lot of programs.
After i installed the new version V1.0.7.98 all problems were gone.
Sorry for the lame english and i dont know if this post is in the correct section of this forum but i hope some of you can benefit from it.
Greetz and c ya ingame !!
PS: after the patch no portforwarding was needed