Mine - via BT DNS servers - came back to life sometime late yesterday afternoon / early evening.

OK, didn't know you were using IPv6. My systems are configured for IPv4 only.
However, the answer to the issue remains the same, BT's servers are not resolving the MS update server. Switching to...

Runnerbean

As at 09.38 3 February.

IPv4 Correct.
Seeing your post I just tried switching between Global and BT DNS servers again.
Using the Google Public DNS works perfectly.
Using BT DNS...

Thanks.
Router was restarted at 10.03 yesterday 1 Feb.
PCs in use are restarted every morning / day.
Update and NSLookup of MS update server via BT DNS remains off line at this time.
PC set to...

Agreed. As a 'fix' using that Global DNS resolves the issue until other DNS servers catch up.

As of 08.00 2nd February - BT DNS server still has the issue.

Still not working here either @ 09.18.

My ISP = BT

I have four PCs here in UK. BT as my ISP.

2 x Acer i7, 1 x HP Envy Laptop, 1 x Linx Notebook.

MS Dialled in to one unit yesterday (30th) & claimed it needed a reinstall from iso. They...