I have a be550 router with upnp active. I have problems of nature in the game Call Of Duty. We are 2 players playing on the same network, with 2 different PCs, with fixed IPs. The first player connects, upnp automatically opens the internal and external port 3074, and therefore the first player has open nat. While the first player is playing, the second player starts the game but finds himself nat moderated. The internal port opened is always 3074, but the external one is not taken correctly. In the game the external port is for example 4567 but the be550 opens the 6789. Why? The game uses demonportmapping to open the ports..
the external port changes often, I think based on the matches it finds, while the internal one is always 3074.

port 46137 changes based on the game.. it is not always fixed. the 3074 on the other hand is fixed.