When doing network evaluation in ambiguous contexts,
spend some time checking each nic and each candidate target ip address.
This may take longer, but options are limited in a routed context.
Get most things automated for the targeted use case.
Still need to handle partitioning and end of install question, add firstboot and add
staged and complete step.
For older Ubuntu 18, the automated installer is debian-installer. Derive from the
prototype debian work, with same limitation about more limited network bringup that
we are stuck with from Debian limitations.