I have used MPD on another player for a while now and the album art is served from my local NAS drive with each album containing a file called folder.jpg.
I seem to be struggling to find the correct base URL for this MPD installation http://<NAS IP>:<PORT>/<SOMETHING>/ARTIST/ALBUM/folder.jpg
Anyone use this? Typically you check the nginx file for the url its serving the art from, but this installation doesn’t appear to make use of nginx.