I had an issue with Planet Rock App premium keep cutting out. Went through support, they decided it was a Planet Rock app issue. So I canceled my premium subscription and started to listen through the TuneIn app, which never cut out.
That is until I have just updated to the new TuneIn app and guess what - its now started to cut out every 4 mins or so, so just the same behaviour as the Planet Rock app had.
Doesn’t cut out on iPhone or iPad.
I don’t have a premium subscription on TuneIn, so it is not a authorising issue. Planet Rock is fine from Sonos Radio as well.