The external keyboard connected through a Dell dock doesn't work before the system boots?
You may find that the external keyboard does not work when connected to a Dell dock before the system boots to the Windows operating system. For example, this can be when you need the keyboard to do things such as entering a BitLocker PIN.
Workaround
- Press the F2 key on the keyboard several times until the computer enters the BIOS setup.
- Select POST Behaviour.
- Select Fastboot.
- Ensure that Thorough is selected in the right-hand side.
- Click on Apply and Exit.
- The system will reboot. Test if the issue is resolved.
Note: The Latitude 7400 notebook must be set to Fastboot > Thorough for the Thunderbolt PBT to be engaged fully. If the BIOS has the Fastboot setting on Minimal the external keyboard through a dock will not work.
This system is working as designed.