During bookup, systemd-networkd is listening for netlink events. This socket's
buffer overflows, especially on new kernels that do more things in parallel,

systemd-networkd[1043]: Enumeration completed.
systemd-networkd[1043]: Starting...
systemd-networkd[1043]: Loaded shared library 'libbpf.so.1' via dlopen().
systemd-networkd[1043]: lo: udev initialized link
systemd-networkd[1043]: enp4s0: udev initialized link
systemd-networkd[1043]: Started.
systemd-networkd[1043]: Notify message sent to '/run/systemd/notify': "READY=1\x0aSTATUS=Processing requests..."
systemd-networkd[1043]: sd-device-monitor(n/a): Failed to get the received message size: No buffer space available

... and then network interface is left in "configuring" state forver. Workaround
is to restart systemd-networkd. A solution is to increase buffer size

$ cat /etc/sysctl.d/99_buffers.conf
net.core.rmem_default = 1048576
net.core.rmem_max = 8388608

Packaging solution here would be to increase buffer by default. Alternative,
the systemd-networkd socket could increase its buffer size to not
overflow. Let me know if you wuld like a patch here for systemd instead.

Cheers,
- Adam