Tried starting up a private multiplayer game through Steam with a friend today, but it didn't work. I've previously run into this issue with Brink, where I had to set up the port forwarding on my router for it work properly. Can anyone tell me which ports DS3 requires for the online multiplayer? That way I can either solve the problem, or cross it off the list of possible causes. Thanks.

A bump, as this issue may be important to quite a few people out there.

Did discover that it was a port issue. When I went into my router settings and had it forwarding all ports, it worked. Learned a new command line tool, so I think I've figured out which ports it requires, but I'll have to wait until I can get another game going with my friend, either later today or tomorrow, to actually confirm that I got them all.

Well, I was hoping to have solved this and have an answer for which ports are needed, but it's strangely started working without my having to mess with my port forwarding on my router. Maybe one of the small mini-patches changed something. If anyone else has issues, the ports that it appeared to need were 8766, 27016, 58046, and 58047. But with things working now without specific port forwarding, I can't test it to be certain.