Can't play on Multiplayer on pc

[Lady_iria]

Hello. I can't use multiplayer. I play through pc. The game is available through steam.

I sign in to xbox live and my friends see me online even though I'm in online mode. When a friend starts a game I can't see it. 
The only way I have to join is through the steam friends list and after a short time it disconnects.
My friend has to save the game and start the game again.

I have tried to synchronize the time.

I have tried to go offline mode and back to online mode on xbox live.

I have tried to go offline mode and back to online mode in steam.

I have checked the NAT.

I have tried disabling the firewall.

I was looking forward to sharing the gaming experience with my friends. Nothing works. Please help.