When Bluetooth refuses to connect, the cause is usually small: a stale pairing, a device in the wrong mode, or a setting. Work through these in order.

1. Check the basics

• Is Bluetooth on in both devices?
• Are they close together (about a metre or two for the first pairing)?
• Is the other device charged? A flat earbud case often fails quietly.
• Is the other device already connected to something else, such as another phone? Many can hold only one or two connections.

2. Put the device in pairing mode

Earbuds and speakers usually need a long press of a button, or taking the earbuds out of the case and holding the button until a light flashes. Check the manual for your model. If it was working before, the pairing mode can have timed out.

3. Turn Bluetooth off and on

Switch it off for ten seconds, then on. Turning on Airplane mode and off again also resets the radios.

4. Forget the device and pair again

1. Open Settings > Bluetooth (look for Connected devices on some Android phones).
2. Tap the settings icon next to the device and choose Forget (or Unpair).
3. Put the device in pairing mode and pair from scratch.

This fixes most “paired but will not connect” cases.

5. Restart both devices

Restart the phone and the earbuds, speaker or car system. For earbuds, putting them in the case for a minute can help.

6. Clear the Bluetooth cache (Android)

Look in Settings > Apps, show system apps, find Bluetooth, and choose Storage then Clear cache. Restart the phone afterwards.

7. Update

Install phone updates and check if the device maker has an app with an update for the earbuds or speaker.

8. Reduce interference

Wi-Fi routers, microwaves and many other Bluetooth devices share the same radio band. Move away from them. A crowded place can also cause dropouts.

9. Reset network settings (last step)

Look in Settings > System > Reset options on Android, or Settings > General > Transfer or Reset iPhone > Reset > Reset Network Settings on iPhone. This clears all saved Wi-Fi and Bluetooth pairings, so you will need to pair again.

If it still fails

Try the device with another phone. If it fails there too, the earbuds or speaker are the problem. If it works with another phone, the issue is on your phone, and a factory reset is the last resort after a backup.

Related

Sound cutting out? Close heavy apps: how to stop apps running in the background and how to speed up a slow phone. Bluetooth also uses power: see how to make your phone battery last longer.