Not sure if this will help (i’m running a different router and VPN) but I can tell you what I had to do.
I’m running a Asus RT-AC88U with third party firmware (Asuswrt-Merlin) and NordVPN connected with OpenVPN session and using the tunneling system that the Merlin firmware has built in. I had to move my PMS from my desktop to another computer then make that new pc tunnel around the VPN so it shows as not on the VPN. I was still having mixed signals that my PMS was available outside my network (sometimes it was showing ok sometimes not) so I looked into it and had to add it also to the DHCP Server settings. now it’s always showing as “Fully accessible outside your network”. Took me a lot of trial and error and I’m assuming you have to have the Netgear Nighthawk behind the Uverse router because it’s how you’re getting your internet to your home.
Not sure if you’re the “tinkering type” but you can look into https://dd-wrt.com/ for possible third party solutions?
