Fix IPv6 or defend your broken implementation

Sounds like Apple Airport-based routers such as the Time Capsule have broken IPv6 tunnel implementations (how broken depends on the firmware version of the TC). Perhaps some help here:

thuktun.wordpress.com/.../ipv6-airport-extreme-update-7-6-3-breaks-existing-ipv6-tunnels

www.sixxs.net/.../Apple_Airport

There is a known problem on Comcast in IPv6-enabled markets when the Xbox One is wirelessly connected and the network has an IPv6 IP. See
http://www.comcast6.net. If you can disable IPv6 on the SMC, that might help.

As far as for inbound ports that need to be forwarded, both the Xbox 360 and One use the same ports:

Port 88 (UDP)

Port 3074 (UDP and TCP)

(And, reportedly for COD Ghosts, Port 3075 (UDP and TCP))

They are not blocked by Comcast. However, since you have both a 360 and a One, getting Open NAT on both at the same time will require a working UPnP implementation on your router. Not sure about SMC, but many home routers have broken UPnP. implementations...

The Teredo IP address message has nothing to do with ports being blocked. It has to do with your ISP's IPv6 implementation. ISPs like Comcast support IPv6 via DHCP, whereas some are currently just using IPv6 to IPv4 tunneling on their routers (which seems
to be flaky with the Xbox One). The only resolution is to get more info on whether your ISP supports IPv6, and if you're using your own router, set the router's IPv6 support appropriately. I got the Teredo error until I manually set my router to DHCP for
IPv6 instead of Auto or 4-to-6 tunneling.

@CrazyDude1965 IPv6 is fully supported on the Xbox One, and a widely accepted network protocol. Not all network connected devices are IPv6 capable, but the Xbox One is. There are other issues that could arise from implementation of IPv6, but that does
not mean that it is not supported on the system, and saying that it is not supported is not true.

According to this documentation:
www.pace.com/.../GP5607.pdf it's a gatway.

Do you know if your connected through an LTE service (mobile), or a carrier-grade service, or if your ISP has implemented IPv6, as native, or as a translation between IPv4 to IPv6?