Game in the Brain

Summary of the Issue

• Pairing the Logitech K780 through the Ubuntu Settings GUI repeatedly failed.
• No pairing key (6-digit PIN) pop-up appeared in the GUI.
• Possible cause: Do Not Disturb was enabled, preventing notifications from appearing.

Working Solution

Using bluetoothctl in the terminal allowed real-time monitoring of the Bluetooth events and exposed the pairing PIN that the GUI never showed.

Steps Used for Successful Pairing

1. Enter the Bluetooth control tool: bluetoothctl
2. Enable and prepare the controller: power on agent KeyboardOnly default-agent
3. Scan to detect the K780: scan on
4. Trigger the pairing: pair EE:EC:73:55:21:88
5. Observe the pairing key in real time:
   • bluetoothctl displayed the 6-digit PIN.
   • Entered the PIN on the K780 keyboard, then pressed Enter on the K780.
6. Finalize the connection: trust EE:EC:73:55:21:88 connect EE:EC:73:55:21:88

Notes

• This issue was encountered on Ubuntu, but similar behavior may appear on other Linux distributions that use the BlueZ Bluetooth stack.
• An untested, unverified possible cause: pop-up notifications may be blocked by Do Not Disturb or other system notification settings, preventing the pairing PIN dialog from showing.
• The K780 requires typing the PIN on the keyboard itself.
• Without bluetoothctl, Ubuntu GUI may hide the PIN due to notification settings.
• Real-time logs in bluetoothctl are critical for debugging pairing issues.