I am trying to play through all four Halos on Legendary with a friend but I cannot join him and vice-versa. I can play multiplayer fine as long as I am not the party leader. I say my NAT is set to 'strict' so I am assuming that is the issue.
I have given my Xbox a static IP from my gateway's options, I then put said IP in the gateway's DMZ. I then got on the Xbox One and put in the IP manually. Rebooted and it is still set to strict.
I have tried all sorts of other options, the RB, LB,RT, LT technique, going to 'power saving mode, etc.
If it helps the Xbox One, 360, my three PCs are all hooked up to a switch which then runs directly to the gateway. There is also another Xbox One on the network who's NAT is set to open as well as another 360, plus other computers and wireless devices.
Any help would be greatly appreciated.