Ok, so here is my setup:
Thompson TG585 v7 router, with UPnP enabled and the following ports forwarded to my Xbox, which has been set to a static IP on my local network:
- UDP 53
- TCP 53
- TCP 80
- UDP 88
- UDP 3074
- TCP 3074
My Xbox is a black 250GB HD model if that makes any difference.
I connect the Xbox to the router via ethernet cable, as well as two other laptops - one pretty much constantly and another from time to time, but usually via wifi.
I have had a couple of problems with being unable to join some multiplayer games, most notably against a friend of mine, who I also cannot get into a party with. He has confirmed that his NAt is open by running the Network Connection Test on his Xbox.
When I run the Network Connection Test, it gets all the way to the last stage - testing Xbox live - but then fails with an exclamation mark icon and gives me a message about NAT not being open.
I have tried turning everything off, starting the router, waiting for it to come up fully, then starting the Xbox with no other network devices attached, but I still get the same issue - what else can I try?