ssh: Could not resolve hostname foo: Temporary failure in name resolution

There are three Ubuntu machines (20.04, 21.04) that are accessible from my workstation via their hostnames foo, bar, baz.

However, after a power outage that affects only the network router (Unifi Dream Machine), all 3 systems can no longer be reached by their hostnames

~$ ssh x@foo
ssh: Could not resolve hostname foo: Temporary failure in name resolution

Restarting machines bar and baz allowed them to be accessible via their hostnames again.

Question: Is there something we can do to machine foo without restarting it so that we can access the system by its hostname foo?

DHCP Settings: