For any client like rmpc or the xfce systray icon you nee to set the host to audiopi.h19.devlol.org

audio files

rsync -aur BestOfRickAstley lol@audiopi.h19.devlol.org:~/music/
mpc --host=audiopi.devlol.org update

Web Interface

http://audiopi.h19.devlol.org/mympd/