I think it's important to say that I've tried everything listed on this website regarding opening my NAT.
I'm using a Bigpond Thomson TG782T.
I have tried the following -
-Forwarding the correct ports to my router/xbox's static IP (seperately
-Tested UPnP with different settings, only worked at the very beginning, even then I couldn't connect to some players.
-Forwarded the ports to the router itself so as to open NAT for the network, theoretically.
-Connecting via an Ethernet cable, which yielded no better results.
Currently, I have the correct ports forwarded to my Xbox, with UPnP on, merely to make it so I can connect on my PC.
The things that really should have caused it to work fine, as I would have guessed it is simply forwarding the ports to the router. However, each of the above methods that I've tried have resulted in a strict NAT setting, according to the Xbox network test.
What I'd like to do is forward these ports over the network, so I don't have to worry about NAT settings on my computer.