Try hibernate next. I've given up on troubleshooting sleep mode in forums but my list to work is BIOS, motherboard and other drivers from the makers. NEVER RELY on Microsoft for the drivers. Do the research on each part maker in your case.
The WiFi driver screwing up the OS? That's rare. I can't only guess why that happened. The only time I saw that was when some client tried a driver update program and it messed up.
I built my custom PC in 2 months ago and I noticed that it has some issues...
For starters, right now when I put it into sleep mode and then try to wake the PC, my PC doesn't wake up and instead I have to force it off and turn it back on.
Secondly, my PC isn't performing as well as it should with the parts in it (i7 6700k, GTX 1080, 16 GB DDR4 RAM, etc.). I just recently had to reinstall Windows 10 because my WiFi adapter's drivers screwed up everything.
Other than that, it seems to be working fine. I will update this post if I find any other issues within the next few days.
My PC: https://pcpartpicker.com/user/HyperFirez/saved/#view=hgwQ7P

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