Galaxy a8 bluetooth tacx neo

Just got a samsung galaxy a8. Zwift app installed. I ride a tacx neo. With a polar h10 hrm.
Power the neo up, open the app, connect the neo and hrm and off i go. Every ride the watts, hrm, cadence etc drop after 20-30 mins and wont just “re-pair” to continue. Ive ended up ending the ride in a huff and giving up! Am i missing something? It totally works well for a while… is it a bluetooth setting or and app setting, ir an android setting? Its doing my head in!