Hello!
This discussion is about IPv6 not being automatically available for Hyper-V virtual machines and related technologies (Windows Sandbox and Windows Defender Application Guard) on Windows 10 Pro v1909 – I did not test it with the Server versions. I would like to see if someone else is capable of confirming my findings and, above all, why this is the default behaviour chosen by Microsoft. Let me explain:
Let’s take a standard fresh new installation of Windows 10 v1909 on a physical machine. One can easily confirm that IPv4 and IPv6 are operational (*). I will call this as HostEnv (short for host environment).
Moving on, we enable on HostEnv the additional features Windows Sandbox and Windows Defender Application Guard. If someone test either of these features, none will be able to connect to an external site using IPv6 out of the box. For instance, the IPv6 protocol stack of Windows Sandbox is there, but not properly configured. Nevertheless, IPv6 is still operational on HostEnv.
One step further, we enable Hyper-V (also an additional feature). Now things become quite interesting. HostEnv loses its out-of-the-box access to IPv6 – as before, IPv6 protocol stack is there, but not configured.
All in all, it seems quite strange to me that IPv6 is not automatically (or out-of-the-box) operational – hey, we are in 2020, aren’t we? If someone could explain it to me, I will be thankful!
Sandro
(*): I have used ping -4 (for IPv4) and ping -6 (for IPv6) as well as https://test-ipv6.com/ .