Night time radio cutting out

We have a new yoto player for our 4 year old who loves the night time radio. However for the last week it has cut out during the night. Sometimes after only a few minutes. The radio picture remains up with no cloud symbol, time remains red, and in the app wifi shows as good but no sound plays. Doing a hard reset as suggested by yoto seems to reset the issue but it will then re-occur often only minutes later.

Daytime radio, card download and playback etc seem to operate fine with no such cutting out issues. Has anyone experienced the same and knows of a fix?