How to wake up monitor?

[coffeecup25]

My pfSense pc/router is attached to a monitor that usually goes to sleep after long periods of disuse.

How can I wake up the monitor without rebooting the router?

[patient0]

@coffeecup25 switching the monitor off and on may help.

Or connecting a keyboard to pfSense and then press a key (not the reboot or shutdown key ;)).