[BUG] SteamVR Link Cannot Find Host if on an IPv6-only LAN

[daggintosh]

Describe the bug
In the (albeit currently rare outside of fixed wireless) event someone has a network that simply does not have an IPv4 LAN, the Steam Link client doesn't have the ability to find the host via the IPv6 LAN.

To Reproduce
Steps to reproduce the behavior:

1. Connect devices to a network without an IPv4 LAN or disable IPv4 entirely.
2. Open Steam Link
3. Steam Link reports that VR streaming can only be done over a local network.

Expected behavior
Steam/SteamVR and Steam Link are able to find each other on the IPv6 LAN if there isn't an IPv4 address for one or either device.

System Information (please complete the following information):

• Steam client version: 1784778118
• SteamVR version: 2.17.6
• Distribution: Arch Linux

Additional context
I would consider this a hybrid between a bug and a feature request, but more toward a bug that's holding Steam back from full IPv6 support.

[Packetdancer]

Unfortunately, yes, this is a known limitation because of how the VR client works (namely, the actual discovery is done by the 2D streaming client, which in the VR case launches the actual VR client), the discovery is limited by Steam's own lack of IPv6 support. Once you are connected, VRLink uses IPv6 just fine...

Sadly, this requires making Steam as a whole support IPv6 throughout, which... would be good, yes, but would also be a large chunk of work, which is why it keeps getting put off.

(It is in the "we really would like to do this at some point" bin, though.)