Disable UPnP at the router & on the computer.
edit: forgot to beg & grovel for XP like a hero.
With the Black Friday deals on Origin / Gamestop / Amazon, a lot of folks are buying the game up. I got two copies for my wife and I and it looks like we are experiencing the same problem. If I join a server, I can play just fine, she can't join on me. If she joins a server, I can't join on her. I definitely think it's similar IP Address related. I was trying to find Error Logs on my computer that would let me know WHY it's not working but can't find anything for the Battlelog errors.
I tried d4isycutter's recommendation to disable UPnP on my and her computers and also on my Router and that did not help.
There is a patch dropping tomorrow so my fingers are crossed:
http://battlelog.battlefield.com/bf4/forum/threadview/2955064769163140123/
At least if the problem persists, we can see if there's better troubleshooting.
Hankspropane - What router/switches are you using on your network, if you don't mind me asking?
