AT&T Fiber UPnP/IPv4 & IPv6

Hi and thanks for reaching Microsoft Xbox gamer's community. My name is Josef.

I'm an Independent Advisor and a Microsoft Xbox user like you.

Hope you're doing great today TB

Yeah, IPv4 is good for your Xbox too, IPv6 was created when IPv4 reach the highest IP available, that's the main difference

uPNP/PortForwarding have nothing to do with Teredo. If I understand it correctly, it's a way to map IPv4 to IPv6.

right, UPnP is already activated and still remains strict, it shouldn't be due to the fact that my device uses a public IPV6. On my console there is IPV4 and IPV6 functional, do Microsoft servers not use IPV6 to connect?

I don't know how to run UPnP and my router doesn't have native IPv6 but I thought that Teredo took IPv4 connections and turned them into IPv6 for the servers or whatever happens.

It might be that your ISP is using IPv6 and tunneling IPv4 via CG-NAT and DS-Lite.

While IPv6 is generally a Good Thing to have (as the Xbox One primarily uses IPv6, and even if you only have IPv4, it will use IPv6 tunneled through IPv4), you might want to check with your ISP if they offer you a "Dual Stack" connection with IPv6 and a
real public IPv4 in parallel.

There really isn't much you can do on the console itself, as it does check automatically what IP protocol your ISP provides, and if it's IPv6, then the console will use IPv6. If it's a Dual Stack, where you have IPv4 natively (not tunneled through IPv6)
and IPv6, then the console will use both, and if it's an IPv4 connection, it'll tunnel IPv6 through IPv4 through Teredo.