Start the “Registry Editor” by typing “regedit” in a elevated command prompt.

Go to: \HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip6\Parameters

Create a new DWORD key named: DisabledComponents and set it to FFFFFFFF (8 F:s).

disable-ipv6-core1

Close “Registry Editor” and reboot the server…

(How? Type shutdown /r /f /t 1 /c “removed ipv6”)

This should disable all ipv6 and ipv6 tunnels.

More info at Microsoft