Comment 4 for bug 1918141

First off, nfs-server starts but doesn't export the unresolvable hosts. The failures do show in systemctl status nfs-server.

To reproduce in a VM you'll likely need something that causes network.target to be fulfilled but actual network traffic to not be forwarded until a few seconds later when network-online.target is fulfilled. Exactly how to do this varies between setups, but adding a unit that fulfills network.target shouldn't be too hard, delaying the network startup in a meaningful way is the tricky one. In any case, I recommend systemd-analyze plot > boot.svg to get an overview of the boot timings.

If I find time today I can take a stab at figuring something out that emulates the behavior we see on physical hardware, for these machines we see between 8 to 10 seconds for systemd-networkd-wait-online.service to complete, with the corresponding delay in network-online.target fulfillment. I think the record I've seen on physical hardware was 30+ seconds on first boot when doing a major OS upgrade trigging a more involved firmware download and NIC restart...