I have 2 unrelated clients with the same issue. One I can use a USB Wifi adaptor and I can get Internet, but the built-in wifi adaptor and ethernet adaptor suffer the same problems as OP but has windows 8, then I have a second client I met with today. Can't even get USB adaptors to work. This client has Windows 10. Have tried everything OP has tried.
Super frustrating. Maybe some kind of malware? I have completed a tddskiller scan, spybot scan, malwarebytes antimalware scan, rkill run, adw cleaner scan.