I have a low energy bluetooth device (client and server) connected/paired to my Moto G5 plus - Android 7.0. After a brief period (when not charging), the bluetooth device is lost - i.e. connection is lost and when I check in 'Settings/Bluetooth' the device is no longer listed. If I 'advertise' the device, I get the 'Pairing request' dialog and can usually re-pair - but not always. Sometimes the server side does not connect and I have to power cycle the phone. On an older Moto G running Android 5.1 I do not have this issue.