De link :
Ativar a depuração manualmente
mkdir -p /etc/systemd/system/systemd-networkd.service.d/
Crie o drop-in /etc/systemd/system/systemd-networkd.service.d/10-debug.conf
com o seguinte conteúdo:
[Service]
Environment=SYSTEMD_LOG_LEVEL=debug
E reinicie o systemd-networkd
service:
systemctl daemon-reload
systemctl restart systemd-networkd
journalctl -b -u systemd-networkd