Not exactly self-hosted but I know many jellyfinners here would cherish this as well.
Looks promising. Does remote controllers work with it?
I expect so.
KDE Connect also works great as a remote control for many things, presumably including this.
I’m wondering what I’ve done wrong with KDE Connect as I could never get it working on any device across 3 different smartphones
Sadly the distributions I tried did not open the required port(s) on the built-in firewall (Bazzite and CachyOS, for two).
I would suggest to disable any firewall and check if you can pair.
You are probably correct that the firewall is the culprit. Good suggestion.
I realize disabling the firewall for testing is OK, but I recommend looking up what it takes to open the ports or app in the firewall instead. I’ve spent my whole career running into and fixing instances where techs disabled firewalls for “testing” and never re-enabled them.