Docker & reverse proxy: how to optimally set up?

[TheDreadPirate]

SOMETHING has to be listening on the host's interface. If you are using bridge networking for NPM with "ports" published, that is still technically "host networking" but only on the published ports.

You mentioned you've tried several IPs for known proxies, but you don't make clear whether you've tried multiple at the same time. Or all of them.

On my system I have plain Nginx running directly on the host with Jellyfin in a bridge network "exposing" port 8096 instead of port publishing. I add the host's IP and the bridge network's gateway IP to the known proxies field.

Additionally, if there are two separate bridge networks, the optimal setup is to have Jellyfin in both networks. However, if Jellyfin and NPM by themselves in their respective networks, I wouldn't bother having separate networks.