The Airport Extreme doesn't support upnp, so pretty unlikely that there's an issue with the feature. Also don't understand the comment about drivers. In what sense would you need drivers for a router?
Well the lack of it maybe an issue.... All I know is 2 or more xbox one's attached to same network with it does not work
And I meant firmware sorry not driver
The Extreme uses NAT-PMP rather than UPNP to perform the same function. My single XBox works fine with a default setup. I wonder if you could put one Xbox in the DMZ and let the other run over NAT-PNP to fix the conflict?