I don’t have a lot of statistics yet but in 3 or 4 tries, turning off Bluetooth via the Control Center for TWO MINUTES OR MORE seems to work 100% to restore connectivity. Give it a try the next time you lose connectivity between your iPhone and your HA’s. Earlier I was only waiting ONE MINUTE before turning Bluetooth on again, and that doesn’t work very well. TWO MINUTES OR MORE seems to be the charm.