Selfhosted

I'm self-hosting my music collection (synology NAS), and while I've liked Poweramp, it only reads local music files, which means I have to copy many GB of music to my phone, even if I'm not particularly listening to it.

The Synology DS Audio app actually does what I want: it caches music locally as you're streaming it, but it reads directly from the NAS.

The only problem with DS Audio is that it sucks as an actual music player.

Are there any Android music players, preferably FOSS or at least privacy-friendly, that will read from the NAS and cache in an intelligent way but also works well as an actual music player?

I did try Symfonium, but couldn't get it to work with Webdav or SMB, plus the dev comes off as a real asshole, so I'd rather not give them money.

EDIT: To clarify what I'm looking for:

• The app must be able to connect to my NAS music collection (through my local network is fine).
• Most importantly, the app must be able to cache my music either as I'm streaming it, or in advance when I'm running through a playlist... then future plays of the song should be from the cache.
• I do NOT want to have to manually download or sync files, which is how I've been doing, and I don't like this at all.

If you've used the Synology DS Audio app, then you'll know exactly the behaviour I'm looking for. It really is a shame that DS Audio sucks as a music player, or else it would be exactly what I'm looking for.