Thanks! As for the Fedora Server instance, I got stuck when it said it stopped and couldn’t figure out what was going on. I never got to firewall settings, but there is a handy post in the Installer page: Android Roon Remote looses connection to Core (daily) - #46 by CRo
I ended up just doing an Ubuntu Server install and it worked almost right away, with no firewall settings needed so far… I prefer Fedora over Debian/Ubuntu, but if it’s working I will just leave it as is and maybe mess with Fedora Server issues in a VM or some other old metal just to see if I can get it working.
Only issue now is that when I updated Roon to v2.0 in Bottles on Fedora desktop, I can’t get it to work at all after selecting an audio output source (it crashes immediately). Tried different runners with no luck… but that’s a different topic from this one. Works in Windows native though.