Dell P2418HT User Manual page 46

Activate the computer and wake up the monitor to gain access to the OSD.
If you press any button other than the power button, the following messages will appear
depending on the selected input:
If either DP, VGA, HDMI input is selected and the corresponding cable is not connected,
a floating dialog box as shown below appears.
or
or
See Troubleshooting for more information.
46 | Operating the Monitor