scnzzh@ZUBT1:~$ kubectl get nodes
The connection to the server 10.0.2.15:6443 was refused - did you specify the right host or port?
Execute below command again:
sudo swapoff -a
scnzzh@ZUBT1:~$ kubectl get nodes
NAME STATUS ROLES AGE VERSION
zubt1 Ready master 3d23h v1.19.2
zubt2 NotReady <none> 3d21h v1.19.2
zubt3 NotReady <none> 3d21h v1.19.2
Executing 'sudo swapoff -a' on the NotReady nodes and wait a moment, status of the nodes will change to Ready.