double nat on console home internet

dispatcher21 wrote:

What firmware are you running on your can?  I have 1609 and have open NAT with my xbox.

Misleading status.  UPnP may be negotiating the forwarding rules so the console "thinks" you have open NAT... but as mentioned earlier, the XLAT464/CGNAT approach breaks the ability to forward ports from the internet to your local network... by design.  It was well documented in the RFC on it like a decade ago.

The same thing happens with PS4 when you set up a router in front of their modem--it negotiates and opens ports locally on your router and appears legit and all... but the higher TMO layers muck things up when the game NEEDS the UDP packets forwarded properly.

Because there is no initial outbound stateful inspection/logging that unsolicited inbound traffic gets filtered/blocked at the upper layers.

In the past some routers were found to track outbound UDP to get around some things in a way to bypass  the need for port forwarding to some degree (like we saw back in the day with the Destiny franchise on some WRT routers)... but highly doubt that will work here (there Nokia device appears very limited feature wise).

Regardless of how our/their routers/modems function  though, it still gets broken at a higher layer.

Again, because of how their XLAT464/CGNAT style setup works (or should I say, DOESN'T work).