Subsonic, Navidrome and Jellyfin

Use a music server as another library, with streaming, caching, favorites and play counts.

Adding a server

Settings → Servers → Add server. Pick the kind (Subsonic/OpenSubsonic, which covers Navidrome, gonic, Airsonic and others; or Jellyfin/Emby), then enter a name, the address (http://ip:port), your user and password. The connection is tested before saving; if it doesn't answer you can try again, fix the details or save anyway.

Each server becomes one more library in the screens bar, with albums, artists, songs, playlists and search. Its catalog is saved, so it shows instantly even without network.

Per-server options

Listening quality: MP3 at 192 kbps by default (little to download, cheap to decode), 320, 128, 96, or Original (no conversion).
Test connection, Refresh catalog, Change details, Remove server.

Streaming and caching

Songs are cached on the SD card as they play (400 MB by default; the least recently used go first), and the next song is fetched ahead of time. Cached songs play without network. You can also Download to library a server's songs, with their tags and cover, into your music folder.

Favorites, ratings and play counts

Liking or rating a server's song also stars or rates it on the server. Jellyfin has favorites but no 1 to 5 ratings.
When a server's catalog loads, its starred and rated songs are added to your Liked list.
Songs you listen to count on the server too (Navidrome can forward them to Last.fm and ListenBrainz if you set that up there). Turn it off in Settings → Scrobbling → Count on the server.

Editing server playlists

While browsing a server, its playlists can be changed, and the changes go to the server:

A playlist's START menu: Rename, Delete playlist (it asks first) and New playlist on <server>.
A song inside a server playlist: Move up, Move down and Remove from playlist.
Add to a playlist on songs from a server offers that server's playlists, plus a new one on it. Local songs keep going to your own playlists: the two never mix.