A search of the comments didn’t turn up any mention of seedboxes. So I’ll throw that hat in the ring as an option.

Maybe self host your own VPN on a VPS and connect the jellyfin server as a client as well as any other devices you want to see that jellyfin server as other clients and configure the VPN server to not override your default routing and to allow clients to see each other? In my head I don’t think that would conflict with your protonVPN connection.

Your traffic would be encrypted between devices so I wouldn’t say https is nessesary and thus no certs needed.

The rubs that occur to me are that I’m not sure you can do this on a free tier VPS which is the only option I see given your financial limitations. And your devices all need to be able to connect to said VPN.

Edit: Slightly less worse English.

Nope. I fiddle until it does what I want. If the thing I’m working on is complex or I’m struggling with it I’ll keep versions of configs. And I back up working configs via an rsync job. Which isn’t a particularly robust solution but I’m content with it for my needs.