Ports being filtered to my Xbox and Port Forwarding has seemed to no longer work after the...

As you noted, a port can only be forwarded to one IP. When you manually forward ports to Xbox A, those ports are no longer available to be forwarded to Xbox B. Placing Xbox B in the DMZ will not help because doing so essentially just forwards all available
ports to Xbox B, and the needed ports are no longer available because you forwarded them to Xbox A. The only way to get open NAT on both at the same time is to use UPnP on a good router that has a working UPnP implementation (many home routers don't). To
try it, enable UPnP on your routrr and remove all Xbox-related port forwards and DMZ.

Sure it's a xfinity technicolor tc8305c gateway.

I've got the ports forwarded on my Xbox, however it seems I can't port forward the same ports for his Xbox one.

Currently my Xbox one has all the ports forwarded and I have an open NAT. He has none with a strict NAT.

Then your router has working UPnP, which the Xbox One is using to automatically forward the needed ports. Or, more likely its UPnP is somewhat broken or slow to respond, and each time you do the "fix" the Xbox repeats the UPnP port forward request and after
enough time the router responds and forwards the port (at which time the One reports open NAT). The point is, if you truly have open NAT, the required ports are in fact being forwarded to your One by some method, either via UPnP or manually.

They is a Option COuld Port triggeing which is just like port forwarding. They is Also a Option for Port forwarding. Here are all the options i Get

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@XalechimThe14th - May I ask if you've (while having Port Forwarding enabled) disabled UPnP? For two good reasons. One being that UPnP tend to overwrite manually configured port forwarding. The second reason might just be the way UPnP is being implemented
on the Arris TG1672G. Where UPnP on this device do not longer work in conjunction with the Xbox One and its latest OS update.