I had a Vivoactive HR and I never had a problem. I have now a new vivoactive 4s since Sunday. It keeps disconnecting from my phone when I leave the room and I have to enter a pin everytime to reconnect. I phoned Garmin. They emialed me with instructions... delete app, clear cache ext. It did not work. I phoned again. They said it is a Samsung fault. I phoned Samsung. Samsung said it is not their fault. I reconnected my olld vicoactive HR. No problems. I have now a new Vivoactive 4S that I can not use. I was a big Garmin fan, but it is very frustrated. No one can help me.