Gaming Notebooks

Hi. I have an Omen laptop from 2018 with an irritating problem:

My laptop is connected  to an external monitor (AOC G2590FX) with displayport to benefit from it's G-sync compatibility. I use the external monitor as the main display, and extend to my laptop display. Sometimes (and this seems to occur at random) my laptop display suddenly goes to black, while my external monitor still shows the same screen. A couple of seconds later, my external monitor freezes, still showing the same screen. Audio will still play for a short time. If i disconnect the external monitor and reconnect it, the screen comes back up, still frozen. The laptop display is still black. At the same time as the problem starts, the laptop fans begin spinning faster.

The only solution is to do a hard reset of the computer. And then sometimes the problem reoccurs just seconds after windows login, sometimes after half a minute, and sometimes doesn't happen before a week later.

I have never had the problem before I bought the monitor, and have sometimes used another monitor for shorter periods connected with HDMI, without problems. The problem has also never occured during high load in a demanding game, but usually just while performing simple tasks.

Has anyone experienced a similar issue? Or does anyone have a solution?

Grateful for any response

Best regards from Norway