Multiplayer don´t work - xBox App shows all okay [PC]

I tried every single thing i found on the net including teredo, firewall, DMZ, ports and so on to get the Multiplayer working but always the same. It´s frustrating.

After i click on Multiplayer i see the Multiplayer-Intro-Movie (every time i start the game). After that it tries to go to Multiplayer-Hopper but i never get there. I always get “lost connection to live” or “Multiplayer not available at the moment. Try again later.”

In my xBox-App it shows that all should be good.

All working
NAT open
connected
… and so on…

I need help please…