Turn Bluetooth off and on, forget the device in Settings → Bluetooth → (i) → Forget This Device, reset the accessory to pairing mode (see its manual), re-pair, then restart the iPhone. Reset network settings if several accessories fail.

The short explanation

Pairing records can get out of sync, especially with cars and accessories paired to several phones. Accessories also have limits on how many devices they remember. Resetting the accessory clears its list.

How it shows up

  • Device not shown in Bluetooth list.
  • “Connection unsuccessful”.
  • Audio drops or connects briefly then disconnects.

What causes it

  • Outdated pairing records.
  • Accessory in the wrong mode or connected to another device.
  • iOS or accessory firmware bugs.
  • Interference or low accessory battery.

How to fix it, step by step

  1. Toggle Bluetooth and restartFrom Settings (not Control Center), turn Bluetooth off and on; restart the iPhone.
  2. Forget and re-pairForget the device, put it in pairing mode, pair again.
  3. Disconnect from other devicesTurn off Bluetooth on other phones/computers the accessory knows.
  4. Update iOS and accessory firmwareUse the accessory's app (e.g. Sony, Bose, car infotainment updates).
  5. Reset network settingsAs a last resort, Settings → General → Transfer or Reset iPhone → Reset → Reset Network Settings clears saved Wi-Fi, VPN and cellular settings (not your data).
How to confirm the fix: The accessory connects automatically and audio plays without drops.

Keeping it from coming back

Keep accessories charged and firmware updated.