What RAX45 VPN Settings are Needed Behind ISP CGNAT?

I have three Nighthawk RAX45 (AX4300) routers at various places. I remote into them using OpenVPN client mainly to reboot the routers when some connected devices are not responding. I recently installed a fourth RAX45 at another location. I am unable to get that router VPN to work. All the routers have the latest firmware.

On this last router, I noticed the public IP did not match the router internet IP, so I contacted the ISP and they confirmed that they use CGNAT. I have found some KB articles that describe changes that can be made to the VPN server and client settings to get the VPN through/around the CGNAT, but I have found nothing that explains how to configure a NG router and VPN client to make it work.

Can anyone point me in the right direction or give me some idea as to the router and client settings to use? Thanks in advance.