Secondary screen freezes after sleep on Win10

Solution 1:

I'm posting this for posterity, because it took me forever to find a quick fix (not permanent) to this problem and I found it on a random forum post, but this is what I do (YMMV).

Open task manager and find "Desktop Windows Manager" or dwm.exe and end it. It gives a warning that the computer can become unstable and shut down, and it has you check a box and click "Shut Down" but it always goes back to normal for me afterwards. The screen flashes a bit but then I regain control of the second monitor.

Again, this is a temporary fix until Windows acknowledges the problem and starts actually providing solutions instead of "restart your computer" but it's easier than unplugging an HDMI cord every time you put the computer to sleep.

Solution 2:

Previously I answered it, but it got deleted as moderator didn't realise I was offering my context and what fixed it for me. I'll make it clearer what has been working for the last few months now:

Exact same issue I had it seems, as intermittent as it was, was a pain. I tried updating drivers. Swapping main screen setting. The second always froze when in extend display mode, only showing mouse movement and the background. Then needed to shutdown once problem occurred to fix. No issue if duplicating.

To the mix was one monitor at home and another in the office.