VPN and Wireguard

Couple things: I have a new MT6000 which replaced a TP-Link. I had a working Wireguard VPN behind the old router, and the WG server was/is running behind the router on a Raspberry Pi. Since replacing the TP-Link with the GL.iNet, I cannot get Wireguard traffic--the VPN no longer works. I had intended to configure a PIA VPN on the GL.iNET, see how things work with it, and then add the WG server to the new router. Again, I would have 2 VPNs on the router--the PIA and the WG. The WG VPN handles 4 different locations, 2 laptops, and, occasionally my Android phone.
Does this make sense? Can it be done on the MT6000? What I the steps I need to do?

The MT6000 can only handle 1 WireGuard client tunnel simultaneously.
Check WireGuard Client - GL.iNet Router Docs 4

So I would say your setup isn't possible with the GL standard firmware.

Thank you for the quick reply. I only want ONE Wireguard account. I was hoping to use PIA just to mask my location. So, now I disabled PIA. I have port-forwarded UDP 51820 to my current WG server (10.x.x.x), and I am not getting any traffic. I cannot ping it. When I log into its local IP (192.x.x.x and try to ping to my laptop's WG ip, it fails. But when I ping with my LAN address, that works both from my laptop and from the WG server.
What's next to try?

Please check everything written here: How to troubleshoot WireGuard

I see (based on your troubleshooting guide) how you can configure the MT6000 router if it is behind the Wireguard server. In my case the WG server is behind the MT6000 router. I have port forwarded the 51820/UDP to my WG server, I have tried External Zone=WAN, LAN, and Wireguard Client. Again, this worked fine with my previous router.

So you are not using the WG server of the MT6000 and instead want to expose the port from another device? What did you do for this so far? Should work without issues, as long as there is no wg server running on the MT6000.