I have an Ubuntu 18.04 server running VirtualMin.
I logged in today to do routine updates to discover it has lost its ability to resolve DNS queries. The server otherwise seems fine but I can't update it.
/etc/resolv.conf tells me that it's using 127.0.0.53 for DNS, which is systemd-resolvd.
systemd-resolve --status lists no nameservers, which will be where my problem is, but I work out where that information should come from.
I temporarily set Google DNS in resolv.conf and did the updates, but a reboot restored the 127.0.0.53 DNS configuration (as expected) and the problem is back.
I *think* VirtualMin is a red herring (it's not used for much and I've been planning to decommission it for years but not today!), and in any case it's just a glorified configuration tool with a GUI so any relevant settings should still be hiding under /etc somewhere, but where I have no idea. Suggestions?