Hi @Roland75
Welcome to the Sonos Community!
When you play Apple Music from within the Sonos app, the speaker you instruct to play fetches the music from Apple Music directly.
When you play from within the Apple Music app, however, it is the phone that fetches the music, and it then sends it via AirPlay to the router, which then redirects it to the Sonos speaker. As a result, the process is more complicated and also relies upon the phone’s connection to the network remaining reliable throughout.
I recommend you only play from within the Sonos app if you continue to experience these problems, but you can try to minimise them when using AirPlay by ensuring that the phone, router and speaker are not subjected to interference, and I recommend not keeping the phone on your person if you are moving around while listening.
Reducing wireless interference
I hope this helps.