Trevor,
My problems with my NAS as a source seem to originate from user permissions and the file path structure.
1) I have to use my admin logon even though I setup another user.
2) I also kept the music directory path
//"Local IP Address"/multimedia/music, seemed like anything else would give it issues.
3) I also need to check it from time to time and "Remount" it under the System - Storage setting. I suspect that my NAS going into a power save mode is the problem there.
Hope that helps. I too often think I need to reboot the RuneAudioPI only to discover I could / should have just remounted the NAS. I'll see my last music list, but can't play any tracks. Turns out the NAS shows a RED Light in System - Storage, if I Remount I get a GREEN Light and we're back to music

.