The MP3-streams of VRT are not working well on Pi Musicbox:
Problem: after several minutes, the music stops and the streaming buffer is filled again. The music starts again, but this repeats thereafter. So, you get annoying interruptions from time to time.
Fix: I manually installed Raspian Lite with newer versions of Mopidy and Gstreamer. Now the VRT streams are working flawlessly.
Maybe it is a good idea to update the software stack of Pi Musicbox?