Nexus 6p - All BT paired devices lost

My phone suddenly ran down to 0% from 15% and turned off. Since restarting I have lost all my paired devices and none of these devices can now be seen by the phone.
I have restarted all devices and phone numerous times, no luck, only pairable devices are others that I had never paired with before.
Last phone update was a week prior to this.
Any suggestions.