FR45s loosing connection with Android phone

My daughter's FR45s regularly looses the connection with Garmin Connect on her Android phone (Samsung Galaxy, 2 year old model). 3 out of 10 times, we simply switch off both the 45s and the phone and reboot them and only then the connection is restored. 7 out of 10 times, after rebooting both, she needs to delete the watch in GC and then re-pair. For some reason, the connections is lost so every couple of days, which is making this really annoying. What are we overlooking?