Comment 18 for bug 1988069

The disable_ipv6 sysctl is interesting, but that is all caught so doesn't trigger the agent to loop luckily, so I don't think we need to deal with it.

One of the only reasons I can think a v4-only network fails for you is that you have either force_metadata or enable_isolated_metadata set to True in your config, since that would try and add the IPv6 metadata address and fail in this way. Unfortunately it doesn't log what it was trying to add when it fails so I can't tell. If you set the mtu to 1280 what addresses does it show on the interface?

I'll post a hack that seems to work for me, but it will need more work and discussion with others to see if it's a good plan. Still don't think tweaking the API call(s) to return a HttpConflict code is a good idea though.