As for me, I just use Syncthing between my devices so I have the same music files in my laptop and my phone. It works well as I don’t often change out the music I listen to, and plus it’s local files so no network required (good on an aeroplane, for example). I personally use an MPD client on my (Linux) laptop, while on Android I use Auxio (Lotus and Chocola are excellent too)

If that doesn’t work for you, there is Jellyfin as well: Finamp for specifically music playback, Findroid for general Jellyfin use. Am not hosting Jellyfin currently so I don’t have anything to add besides that, but do check out the docs if you need help setting up / maintaining it!