You can try this:
"A. To check any timers will wake your machine that are in effect, run
You'll get a list of any active wake timers on the system."
On my computer, I had to use an elevated command prompt for it to work.
Right-click on the Start Button and choose "Command Prompt (Admin)"
There's more to try here:
powercfg -waketimers did not show anything at all, so I guess that's good.
powercfg -lastwake said the my Ethernet was the cause for last wakeup.
I followed the advice from How To Prevent Your Computer From Waking Up Accidentally and will see if that does the trick.
It does seem to work now. The NUC seem to stay off. Thanks! :-)
After installing Windows 10 Version 1511 (10586) the problem has appeared again. It is still the Ethernet that wakes up my computer, but there are no waking timers active.
The old advices from the above thread does not seem to work anymore. Any suggestions?
I think the setting that fixed it was reset with that big Windows 10 update I installed the other day. Seem to work again now.