I didn’t manually disconnect my Pokémon GO Plus + from my smart device, but it was disconnected. Why?

Please see here for more details about how to reconnect your Pokémon GO Plus + to your device. One of the following may be the cause of your lost connection.

・ The battery has been drained.
・ Your smart device and Pokémon GO Plus + are too far apart.
・ Your Bluetooth connection is unstable.
・ There is an obstacle that interferes with your connection.