IPv4 configuration fails in installer when IPv6 auto configuration succeeds

[Andreas Ott]

Ubuntu 16.04 LTS amd64 server install ISO

Expected:
Installer should prompt for IPv4 network config to be entered manually if IPv4 auto configuration fails, even if IPv6 auto configuration succeeded. This should be dual-stack, operating independently from each other.

What happened instead:
Server is IPv6 only after reboot, even when IPc4 network settings were entered manually during install

I am trying to install a server VM on a dual-stack network segment that has no IPv4 auto configuration (no DHCP) but has IPv6 router advertisements (IPv6 auto-assignment works). IPv4 addresses must be assigned manually on this segment.

The installer will do automatic network configuration with IPv4 failing, and IPv6 succeeding, then stop at the point to ask for DNS server IP(s). DNS information is not supplied through IPv6 mechanism of self-assigning an IP address. I can use "Go back" and manually configure IPv4 settings, and they are retained for the install process, but are not permanently written to /etc/network/interfaces . After reboot, the server is IPv6 only, minus working DNS server settings.

Additional info:
The network configuration works if I install on a network segment that has no IPv4 and no IPv6 automatic configuration, in this case the installer shows that all auto configuration failed and asks for all network configuration to be entered manually.

The network configuration works if I install on a network segment that has IPv4 DHCP to provide network auto configuration (with or without IPv6).

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Andreas Ott (kndreas)]

More info:
I tried the install one more time, no IPv4 auto configuraiton, but with IPv6. I manually added an IPv6 DNS server when it asked for one, and the server finished installing (presumably with downloading packages or updates). After reboot, it does not show the manually configured IPv6 DNS server in /etc/resolv.conf or /etc/network/interfaces, so the server is online "IPv6 only" but "unusable".

[Ubuntu Foundations Team Bug Bot (crichton)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. It seems that your bug report is not filed about a specific source package though, rather it is just filed against Ubuntu in general. It is important that bug reports be filed about source packages so that people interested in the package can find the bugs about it. You can find some hints about determining what package your bug might be about at https://wiki.ubuntu.com/Bugs/FindRightPackage. You might also ask for help in the #ubuntu-bugs irc channel on Freenode.

To change the source package that this bug is filed about visit https://bugs.launchpad.net/ubuntu/+bug/1580734/+editstatus and add the package name in the text box next to the word Package.

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