Problem with a bluetooth headset

good morning I have a problem with my liberty 2 pro headphones. purchased 3 years ago. left earphone used individually, everything ok. used individually, the right earphone disconnects as soon as I move 3 meters away. used at the same time it does the same thing, so as soon as I move away from the phone they feel bad/block/disconnect both at the same time (because the right one controls which doesn’t receive Bluetooth well, I think. what can I do? thanks