Can't Connect to Xbox Live Party

I cannot connect to an Xbox Live Party on my PC through the Xbox Game Bar on Windows 10. I am connected via Ethernet.

It says "Connecting..." then that there was an "error".

I have the BGW210 - 700 router.

I have followed every step listed here:

https://support.xbox.com/en-US/help/hardware-network/connect-network/troubleshoot-party-chat

I've rebooted my gateway, removed my VPN from PC, disabled my firewall completely, updated all network drivers, reinstalled the xbox clients, and nothing has worked.

I've read 100+ articles on this issue and have opened up all the necessary ports:

88 (UDP),

3074 (UDP & TCP),

53 (UDP & TCP),

80 (TCP),

500 (UDP),

3544 (UDP),

4500 (UDP),

60209 (TCP & UDP)

Windows 10 Xbox Networking diagnostics tool used to say my NAT was "Moderate", but after doing the above it now says my NAT is "Open".

The issue still persists, however.

I did not set up a static IP, but the port forwarding allows me to select my device by name so I assume I don't need to?

I've run out of things to try and my next step is canceling AT&T Fiber and going back to Spectrum.

:)