This happened to me too, and what I learned is that the Omnia uses the Knot DNS resolver, which re-enables itself after updates and this breaks everything if you have made certain customisations.

The fix is to disable this with "echo 'Uninstall("knot-resolver", { priority = 60 })' >> /etc/updater/conf.d/user.lua" over SSH so it stays disabled. You can do this for any service you modified or disabled, and the documentation barely mentions this (it's a real showstopper bug until you diagnose it - no connectivity whatsoever).