Help - Windows 11 lost internet connectivity

[Carlusha]

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@TimCurtiswrote:

Well recovery from Win11 to Win10 was pretty quick and seemly painless.

I'll leave it a few days before I go again to Win11.

Thanks for trying to help but it looks like I'd really corrupted something that wasn't fixable.

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OK, great but even at that point, you have nothing to lose by running @gg30340 's suggestion of :

The last thing I can think of would be to run  check disc in a command prompt chkdsk C: /r which should find any damaged or corrupted Windows files and replace them. 

This will ensure you are "uncorrupted" prior to your second attempt.

[licquorice]

Hmm, you shouldn't have to run any commands on either W10 or W11 for IPv6 to work.

[WSH]

The Sc command is a way to update the registry.  That will be where the corruption is.  I’m not sure Sc was updated beyond Windows 8.  Personally, I think using regedit is a safer bet.

As Liquorice says, Windows has been dual stack since Windows 7 and you should not need to run anything to get IPv6 to work.  In my experience any problems with IPv6 are usually the router or Windows temporary addressing, where Windows refuses to give up an IPv6 address even though it has deprecated it.  If you had IPv6 working and it suddenly stopped that will probably be the reason.  Windows 11 is a lot better behaved than Windows 10 in this respect.

[TimCurtis]

Looks like one of my VPNs (FastestVPN) prevents the IPv6 connection being established.

Had this installed on my PC and a laptop both of which couldn't get an IPv6 address but as soon as I uninstalled it IPv6 was back.