The connection to the server 192.168.1.111:6443 was refused

when I restart the ubuntu,and type kubectl get nodes
It always show
``
lal@kmaster:~$ kubectl get nodes
The connection to the server 192.168.1.111:6443 was refused - did you specify the right host or port?


you can use these command to solve this issue:
1. sudo -i
2. swapoff -a
3. exit
4. strace -eopenat kubectl version

try kubectl get nodes now.