k logs -n kube-system kube-router

F0320 12:24:52.703516    3291 network_policy_controller.go:419] Failed to run iptables command to insert in INPUT chain running [/sbin/iptables -t filter -I INPUT 1 -m comment --comment kube-router netpol - 4IA2OSFRMVNDXBVV -j KUBE-ROUTER-INPUT --wait]: exit status 4: iptables v1.8.10 (nf_tables):  RULE_INSERT failed (Invalid argument): rule in chain INPUT

See also

• kube-router
• Play with Kubernetes: kubeadm init