Setting up Port Forwarding for AT&T (ISP) BGW320-500 Router/Modem

Looking to get a Wireguard server set up on a Flint 2 router.

I have an AT&T ISP Router/Modem AT&T HUMAX BGW320-500. From the setting menu. I'm looking to set up the port forwarding via the Custom Service entry. What are the following entries do I need to fill out?

Global Port Range ??
Base Host Port ?
Protocol - should I use TCP/UDP, UDP or TCP.

  1. Confirm if the ISP router has the public IP
  2. Regarding the Port Forwarding for WireGuard Server:
    Global Port Range: 51820
    Base Host Port (GL router WireGuard Server): 51820
    Protocol: UDP

It seems that the WAN IP (Base Host IP?) of the GL router is missing, I think the IP needs to be set before it can actually be used, like this:

Have you considered putting the AT&T gateway in bridge mode and using the Flint 2 for both routing/wifi and WireGuard? Might make things easier and from my observations putting the gateway in bridge mode is a pretty common thing people do with the BGW320 for a variety of reasons.

@doczenith1 You mean something like this:
https://community.ui.com/questions/BGW320-500-Bridge-Mode-and-or-IP-Passthrough-Question/99786f13-1f76-46dd-9801-7102fd1d44d7

  1. Confirm if the ISP router has the public IP - confirming
  2. Regarding the Port Forwarding for WireGuard Server:
    Global Port Range: 51820
    Base Host Port (GL router WireGuard Server): 51820
    Protocol: UDP

I set the above and the port forwarding is working successfully.

Yes, that is what I'm referring to.