The problem seems to have "fixed itself". All I did was use the fixit (didn't work at the time) and turn my modem and computer (via shutdown) off and on! Initially didn't work, then later I noticed I was getting Windows updates. Windows 10 installed okay. My internet was working. Then another session Windows update failed again for the same reason. So I shut down my computer and restarted. It was fixed and since then no problems. I hope this helps, best to try simple solutions first.
Edit: the problem reoccurred, so after shutdown and restart I did a full scan with Windows Defender, which found nothing. Your link for the Microsoft Safety scanner was broken. Since my Windows update is again working and up to date, I'm hoping this shows I don't have a virus.
Your other link seemed to be for Windows 8.1, so I didn't try it as I've now got Windows 10. Any more suggestions?