How to re-pair the keyboard with the USB dongle:

1. For 2.4G mode (ensure the keyboard is currently in 2.4G mode):

• Insert the USB receiver into your device.
• Turn on the keyboard and press the Esc and + buttons simultaneously for 3 seconds to enter pairing mode. If the USB mode indicator light starts flashing, it means the keyboard has entered pairing mode.
• Once the keyboard is in pairing mode, quickly unplug and plug in the USB receiver.
• This will successfully re-pair the keyboard with the USB dongle.

How to reset the keyboard Bluetooth:

2. For Bluetooth mode:

• Turn off the keyboard.
• Long press the ESC and 3 buttons together (the 3 button on the main keyboard, not on the numeric keypad).
• While holding these two buttons, turn on the keyboard until the Bluetooth channel 1 indicator light flashes quickly.
• After that, you can choose the desired connection channel to connect the keyboard to your devices.

1. Ensure that the keyboard is fully charged before attempting to connect it.
2. Confirm that the keyboard is in the correct mode by checking if the corresponding connection channel light is flashing as expected.
3. If you are using the USB dongle to connect the keyboard:
   • Unplug and replug the USB dongle into your device.
   • Try using a different USB port on your device.

   If you are using Bluetooth to connect the keyboard:

   • Delete the keyboard's Bluetooth pairing from your device's Bluetooth listing.
   • Restart your device.
   • Repair the keyboard with your device by following the pairing instructions.
4. Attempt to connect the keyboard to other devices to determine if the problem persists.

If the problem continues, please refer to the re-pairing and resetting Bluetooth steps mentioned earlier to re-pair the keyboard with the USB dongle and reset the keyboard's Bluetooth connection.

1. Ensure that the keyboard is fully charged before proceeding with any troubleshooting steps.
2. Reset the keyboard by following these steps:
   • Turn off the keyboard.
   • Long press the ESC and 3 buttons together (the 3 button on the main keyboard, not on the numeric keypad).
   • While holding these two buttons, turn on the keyboard until the Bluetooth channel 1 indicator light flashes quickly.
   • Once the keyboard has been reset, you can choose the desired connection channel to connect the keyboard to your devices.

1. Ensure that the keyboard is fully charged, as a low battery can affect its performance.
2. If you are using the 2.4G USB receiver to connect the keyboard:
   • Unplug and replug the USB receiver into the USB port of your device.
3. If you are using Bluetooth to connect the keyboard:
   • Delete the keyboard's Bluetooth connection from your computer's Bluetooth connection history.
   • Restart your computer.
   • Re-pair the keyboard with your computer by following the pairing instructions.
4. Try connecting the keyboard to other devices to determine if the issue persists.

The XK21 keyboard does not have the N-Key Rollover feature.

If you have lost or misplaced the USB dongle/receiver for the XK21 keyboard, you can purchase a universal USB dongle/receiver from our official website. Please visit the following link:https://www.protoarc.com/collections/all-products/products/usb-receiver

Before using the new USB dongle/receiver, please ensure that you re-pair the XK21 keyboard by following these steps:

1. Insert the USB dongle/receiver into your device.
2. Turn on the keyboard and press the Esc and + buttons simultaneously for 3 seconds to enter pairing mode. If the USB mode indicator light starts flashing, it means the keyboard has entered pairing mode.
3. Once the keyboard is in pairing mode, quickly unplug and plug in the USB dongle/receiver.

By following these steps, you will successfully re-pair the keyboard with the new USB dongle/receiver.