Maybe the cooler or rad is clogged up with dust and junk, try cleaning everything out if the power solutions don't work. The fins that get water flowed over them can get easily clogged up so you might want to clean that too.
Are there 2 networks (a 5g and 2.4g?) enabling only the 5g wouldn't give you much of a difference from what I've seen in my testing. The 2.4 network is also good for older devices that can't handle 5g.
You might have shorted connections on the board, limiting it to only the power rumble thing... Removing the gunk should fix the problem but if not just buy another board or a new controller.
Kaby Lake only works on windows 10, if you are trying to use windows server for workstation applications I think a Xeon would be a better CPU to use because of the better performance and compatibility.
Something you can do right now cheaply is look on the used market for something like a monitor. Most people don't classify their 1080p 60hz monitor as "gaming" so the prices are surprisingly low. I picked up my AOC i2367f for only $40 and it was used for 20 minutes when I picked it up. Your luck may vary so just keep hunting.