xbox (on PC) multiplayer not working (Teredo cannot qualify & NAT type moderate)

I've been trying to play fh4 & fh5 with friends and "Teredo cannot qualify" keeps randomly popping up. Usually I press the windows "fix it" button and restart the PC and it works, but sometimes it doesn't and I just have to wait a day or two until it randomly gets fixed somehow.

But even when teredo isn't the problem, "NAT type: moderate" pops up, and even though all the ports for FH5 are open, sometimes it still doesn't get fixed.

Any ideas how to permanently solve any of these problems? (I had tried many solutions, but they usually work for one time and then just stop working)

:)