LG C5 OLED evo TV will not pair with Bluetooth headphones or speakers

The checks in more detail

Put the headphones or speaker into pairing mode, usually by holding a button until the light flashes, and in Sound Out choose Bluetooth, then search for the device and pair it. If it has paired before and fails, select it in the list and choose Remove or Unpair, then pair it again, since a stale record is the commonest reason for drops. The C5 supports a limited number of Bluetooth audio devices at once, so remove ones you no longer use. If the sound lags behind the picture, use the AV Sync adjust in Sound settings, and look for a low-latency mode on the headphones; wireless audio adds some delay.

If the device drops after a short time, check its battery, keep it within a few meters and away from other Bluetooth and 2.4 GHz devices such as a Wi-Fi router, and test with the TV's Wi-Fi on 5 GHz. Turn the TV off and unplug it for a minute, as unplugging clears the Bluetooth stack better than a normal power-off. Update webOS in Settings, General, About This TV, since LG fixes Bluetooth behavior in updates. Some devices only work with newer Bluetooth codecs, and the TV may default to a basic one, so check the device's manual.

If the TV finds no Bluetooth devices at all, even phones, the module may be faulty. For a soundbar, eARC is the better connection. If the headphones pair but cut out when you walk to another room, check the range: Bluetooth audio from a TV normally works within about ten meters in the open and much less through walls. Keep the TV's own Wi-Fi and the headphones' battery healthy, and test with a different pair of headphones to learn whether the TV or the headphones are the problem. If a second pair works well, the first pair is old or faulty.