Bluetooth connection

Bluetooth connection with the Edge Explore 820 seems to be a challenge. Some times, not often, it connects immediately to my phone. Other times it takes 15-30 minutes to connect. And sometimes it just won't connect. At the same time, my Garmin Vivoactive HR is constanly connected to my phone. Seems the BT implementation in the Edge is somewhat buggy. Any ideas on how I can improve this?