Newly set up k8s cluster fail to work

I am trying to set up my K8s cluster in ubuntu follow below instructions

Everything seems fine in only few minutes, after that, everything die, kubectl cmd not working any more

The connection to the server was refused - did you specify the right host or port?

coredns keep in pending status

kube-proxy, kube-scheduler always change from CrashLoopBackOff Error to running

what I do is keep restarting kubectl
systemctl restart kubelet