I haven't made any software or hardware changes whatsoever. The NUC is still running, the monitor says there is no signal and it goes to sleep. I have to reboot the PC usually to get it going again, though opening the monitor's menu has also kicked it back to life once, seeminly at random.
I know this is totally vague, but anyone have any ideas? Is more likely windows or the monitor?
Windows is set to never shut down or sleep/no screen saver. This just happens in the middle of active use.
I have never seen reports of any issues like this before. I wonder if you are seeing a communications issue (typically caused by a poor quality HDMI cable).
Please download and run the Intel System Support Utility for Windows and have it save the report to a file. Then, using the paperclip icon below the edit window (below the B (for Bold) button), upload and attach this file to a response post.
Also, what monitor(s) do you have connected? How are these monitor(s) connected? Straight through cables or dongles (HDMI-to-HDMI, USB-C-to-HDMI, etc.)? What is the rating on the cables? HDMI 1.4? HDMI 2.0? DP 1.2? DP 1.4?