I had a play around with static vs non-static NAT port mapping for my son's xBox One. Under my current setup the only port forward I have is in on port 3074 for both TCP and UDP, and run a transparent proxy for HTTP traffic. With static NAT port mapping switched off it reports a strict network configuration and an open configuration with it on. Ran some packet captures and examined the states tables for both configurations. In both scenarios the xBox only generated the following traffic:
DNS requests on TCP port 53
Teredo tunnelling from UDP port 3074 to port 3544 on a remote sever
Queries to TCP port 443 on several remote servers
Queries to TCP port 80 on several remote servers
All originating ports from the xBox to TCP 443 and 80 were all in the range 49916 to 49930, however I'm sure this range will increase when multiplayer gaming so unless I want to forward a rather large range of ports to the xBox, static NAT mapping appears to be the only way for it to work. I'd need to do some more packet captures under various usage scenarios to see if maybe I can narrow down the static NAT mapping port range to something smaller rather than all 65535 ports.