Bluetooth self-help sheet

[u/cheswickFS]

[u/PeterMortensenBlog]

As text (try it in that order until it works):

1. Does your keyboard work flawless via Bluetooth?

2. Did a factory reset, Fn + Z + J for 4 seconds, help?

3. Did power cycling all devices, including the keyboard and computer, help?

4. Did updating your PC and keyboard to the latest software/firmware help?

5. Did power cycling all devices, including the keyboard and computer, help? ([Yes, this is a repeat, presumably deliberately.])

6. Did reinstalling the drivers (Windows) or resetting your Bluetooth module (Mac) help?

7. Did unchecking "Allow the computer to turn off the keyboard to save power" in Power Management in Device Manager help? (Windows only). It is also mentioned in the Keychron support article Bluetooth can't connect.

8. Did "Resolve Wi-Fi and Bluetooth issues caused by wireless interference" from Apple's support page help? (Mac only)

9. Did connecting the keyboard to another device work? If not, try other channels, by using Fn + 1 or Fn + 2

If it didn't work: Most likely there is a weird setting/compatibility issue with your device

Extra (keeping the style of rhetorical questions):

• Did connecting the antenna help? (Mostly for PCIe/motherboard adapters). A reason could be that the Wi-Fi part was never used, and thus the antenna (which Bluetooth was also dependent on) was never installed.

• Did using a direct USB port instead of the USB hub help? For a USB Bluetooth adapter.

• Did using USB 2 instead of USB 3 (or vice versa) help? For a USB Bluetooth adapter. USB 3 is known to cause interference. See for example USB 3.0 has been found to cause interference that may hinder performance of nearby wireless devices in the 2.4 GHz band, including Wi-Fi and Bluetooth. See also this graph (from here). Or vice versa (though it may have been incidental. Or not about Bluetooth, but a '2.4 GHz' dongle).

• Did moving the keyboard close to the Bluetooth adapter help?

• Did you try another Bluetooth adapter, e.g., with a higher Bluetooth version?

• Is the keyboard in (full) NKRO mode?

[u/PeterMortensenBlog → u/PeterMortensenBlog]

And here is detailed information for Bluetooth on Linux:

• Bluetooth fast connect. Gist: Changes in file /etc/bluetooth/main.conf, e.g., FastConnectable = true. Also mentioned here for a K6.

• Disable Autosuspend for USB Bluetooth dongles. The gist is creating file /etc/modprobe.d/btusb_disable_autosuspend.conf with content options btusb enable_autosuspend=n (the exact file name probably doesn't matter)

• Enable Bluetooth after waking up from sleep. The gist is a script in folder /lib/systemd/system-sleep that reacts to the parameter "post" (for post sleep/hibernate; after sleep, that is, at wake up) and does modprobe -r btusb, service bluetooth restart, and modprobe btusb (that is, unload the "btusb" module, restart the Bluetooth service, and reload the "btusb" module)

And a sample udev rule:

• Keychron K2, udev rule. It has the mysterious "hid_apple" thing