I've been franticly searching to find a solution to dns problems related to vpnc tunneling in Ubuntu Gnome 17.04 and been following this thread. Why on earth would this work on the live image and not after installation? I know this is a bit off the topic but I getting desperate. I am not using valet but I saw a clear relation between what I am experiencing with my vpnc tunnel and the problems described here concerning dns resolve.
It actually looked like it would solve my problems as well. I'm already reverting to 16.04.3 as that release has no issues whatsoever in relation to dns, slow boot and such. @carlihland indeed, the 17.04 is a mess, solutions work one day but not the next, all this because of updates and the unpredictable situations generated by system-resolved.
I'm afraid we'll just have to wait until Zesty is officially released.
I haven't done any tests or fixes myself yet, I'd probably make things worse. Edit: After a bit of research, according to this, taken from this forum thread, 16.10 has the same issue for the same reason, and users are experiencing the same kind of DNS issues. I hope this comment helps others know they are not alone.
I've tested it enough to make sure it breaks nothing in Ubuntu, Arch and Fedora. Indeed the branch is a mixture of cleanup and configuration change because I needed to push frequently in order to try the different solutions in different distros (Ubuntu 17.04, Fedora and Arch) making sure nothing broke.