To connect your iPhone 8 Plus to your plt-m165 Bluetooth device again, follow these steps:
1. Make sure Bluetooth is enabled on your iPhone.
2. Put your plt-m165 device into pairing mode (check its manual for instructions on how to do this).
3. On your iPhone, go to Settings > Bluetooth.
4. Wait for your plt-m165 device to appear in the list of available devices. Once it appears, tap on it to connect.
5. Follow any on-screen prompts or enter a passcode if required.
6. Once connected, you should regain the ability to use your plt-m165 Bluetooth headset with your iPhone 8 Plus.
