Hmmm, Interesting information.
The comment about very few routers handling two xboxes going back to the original, makes me wonder why I have to do a factory reset on my 360s every time I change routers or connections on the 360s to make the NAT OPEN up. Also I've been using two 360s for a while. Others have been using 3 or more. Hmmm. I'm not fully confident in MS fully putting it on the router. Makes me wonder what router models they consider handling of two xboxes? Most of my testing has been over several D-Link routers and non D-Link as well. This is with 360s mind you as I don't have any XB1s.
I presume this uPnP certificate handling behavior is behind the scenes in FW and is not viewable from our side of the fence.
I'll pass this along to D-Link for review. Thank you for sharing this information. I'll post back if I hear anything.
In speaking to xbox live networking guys again today here is what I was told...
"with internal testing we found that instant on only caused this issue because most routers are not resetting UPNP certificates. While this is an issue it does not cause nat. That is still on the routers end.
Nat with multiple consoles has been an issue since the original xbox and while instant on does exacerbate the issue the issue at its heart still lies within the local networking equipment. There are very few routers that can handle two xboxes."
Thoughts? Any way to check if upnp certs aren't being reset as ms claims to be the case?