Hi,
I am running Zorin OS on a Dell XPS 9510 laptop with an external ASUS MB16AC display connected to it through the display port.
Every now and then I had the annoying problem that the external display started to turn off after a couple of minutes and then back on after a couple of seconds (especially if you were not working 'inside' windows on the external display for a couple of minutes), causing all windows on the external display to move over to the laptop screen etc. I thought the problem was perhaps related to the NVIDIA driver, the display port cable, the external monitor, but could not find a root cause.
I just stumbled on a workaround (and if you know it, you can also find the workaround on the Ubuntu forums): just connect a headset to your laptop and the problem is gone!
Regards,
GW