Earlier quoted context omitted.
I mean, I know it's too late to help you, but running "powercfg.exe /lastwake" after a windows computer wakes from standby will tell you exactly what woke it up, if it knows. I've never had it return with "unknown" once in over a decade, but some people I know have. if you can find all the things waking the computer, and fix those things, it will never wake without user intervention. usually, for me, it's been device…
I have NEVER in my life ever gotten a useful output from `powercfg.exe /lastwake`. I'm honestly surprised to hear someone mention it as working, I thought it was the sort of thing that was just copypasted on clickfarming tech-help blogs without any sort of verification that it actually works. In fact I just tried it again on 4 computers and every one of them said "Wake History Count - 0".
also, run the command as an administrator. not just using an account that is an administrator. use an elevated cmd prompt or PowerShell window.
if you're doing all that, idk what's going on.
You can, however, see what devices are capable of waking your machine, and then disable them, by using the commands in my other comment: https://news.ycombinator.com/item?id=28647492