Cannot get Plex to connect outside the network

I am trying to get a home media server set up over my network. I have done this before, however I have added a few layers of security to my network and I am now having problems.

I am using Wiregaurd via proton VPN hosted on the router (GL-MT6000).

Plex works fine inside the network, TV, phones, laptops, etc can all connect. When I try to set up the outside network connections using port 32400 (as advised by Plex) it fails. Turning off the router VPN allows Plex to connect outside the network, so I have isolated the problem to Wiregaurd on the router.

Here is my config:

[Interface]

Address = xx.xx.xx.xx/32

ListenPort = 32400

PrivateKey = [redacted]

DNS = xx.xx.xx.xx

MTU = 1420

[Peer]

AllowedIPs = 0.0.0.0/0

Endpoint = [redacted]

PersistentKeepalive = 25

PublicKey = [redacted]

I would like to avoid doing a split tunnel if I can. (Although I haven't quite figured out how to make that work yet either) Since plex works while not connected to the VPN the split tunnel would be a solution although less secure.

Any advise would be very appreciated.