Dell C2722DE 27" 16:9 IPS Video Conferencing Monitor - Manual (Page 51)

Setting up the monitor | 51
Go to System Settings
In the drop-down menu of When I press the power button , there are a few options
for selection namely Do nothing/Sleep/Hibernate/Shut down , and you can select
Sleep/Hibernate/Shut down .
NOTE: Do not select Do nothing , otherwise monitor power button cannot
sync with PC system power state.