In reply to a post by Banger:

Two Win 10 Pro machines one wired one wifi, neither were affected.

Did your Dec 2016 Update Install correctly?

Yes, although one machine is taking 15 minutes at the configuring windows updates stage.

Both my PCs are Win 10 Pro, one is up to date with Win 10 V1607. The other I've delayed the AU being applied.

Neither have had the problem.

I can put that idea to bed then

It is said that it had to do with fast start option and an old ip 169 issue.
This maybe why Microsoft said use restart to fix.
Restart does not use fast start option.

In reply to a post by flippery:

It is said that it had to do with fast start option

Which Win 10 has that? My Win 10 Home doesn't.

& what's "an ip 169 issue"?

In reply to a post by XRaySpeX:

In reply to a post by flippery:

It is said that it had to do with fast start option

Which Win 10 has that? My Win 10 Home doesn't.

& what's "an ip 169 issue"?

have a look at power options>choose what the power buttons do>click on change settings that are currently available and you'll see the check box for fast start.
I prefer it unchecked...

When I said I don't have the fast start option, I meant it. I know where to find it if I had it but it ain't there! All that shows is Sleep & Lock.

If hibernation is disabled it will prevent fast start from showing.

In reply to a post by XRaySpeX:

what's "an ip 169 issue"?

When Windows can't obtain an IP address from a DHCP server for an active LAN port (and not assigned as static address) - it will assign it an address starting 169.254 ( link local). So a if your LAN port has address starting 169 it could signify issues connecting to DHCP