A. 1. Go to Settings > Bluetooth and toggle Bluetooth off and on. 2. Forget the Bluetooth device and re-pair it by going to Settings > Bluetooth > [Device Name] > Forget. Then, reconnect the device.
B. 1. Restart your phone to refresh the Bluetooth settings. 2. If the issue persists, reset network settings by going to Settings > System > Reset options > Reset Wi-Fi, mobile & Bluetooth.