First update to the latest Windows build by running the Windows Update Assistant at https://www.microsoft.com/en-us/software-download/windows10/
Note: this may initially trash your devices (it did for me big-time: no ethernet, no wifi, display stuck in low res with driver error message!).
But: no worries, that was just a means to an end because we straight away go to Settings and choose the option to go back to the previous Windows build.:
That's it! Back in your familiar build, Windows Update now works fine. (And any devices trashed by the update are back to normal, of course.)