NPM Unraid Docker container - custom network

[ripeart]

I've got niginx proxy manager running on custom network (br0) with a fixed IP, I've got my redirect site (Overseer) on the same network with a fixed IP. The domain has an A record that points to my WAN. In my router 80 and 443 are forwarded to npm IP, and at the nginx app I've created a proxy host pointing the URL to the internal IP of the Unraid server. However I'm getting a 521 error for the domain. What am I missing? Is there a forwarding in a npm config file somewhere that I need?

This all works when I put both apps on the 'bridge' network btw.

Unraid IP - 192.168.168.100

NPM (br0) - 192.168.168.101

Overseer (br0) - 192.168.168.102:5055

NPM Proxy host 192.168.168.100:5055

Router forwards ports 80,443 to NPM (192.168.168.101)

Still no dice. Is there a config file in NPM I've got to adjust?