How to fix Kubernetes Cluster Error IP:6443 , localhost:8080 was refused

First issue was IP:6443 was refused.

Recently I build kubernetes 3 nodes clusters and forget to change IP as static. After a few days the master node IP was changed and I received the following error while running kubectl command.

myo@master-node:~$ kubectl get nodes

The connection to the server 192.168.1.132:6443 was refused - did you specify the right host or port?

I found the following command solved the issue.

sudo -i

swapoff -a

exit

strace -eopenat kubectl version

Here is the result.

myo@master-node:~$ sudo -i

root@master-node:~# swapoff -a

root@master-node:~# exit

logout

myo@master-node:~$ strace -eopenat kubectl version

openat(AT_FDCWD, "/sys/kernel/mm/transparent_hugepage/hpage_pmd_size", O_RDONLY) = 3

openat(AT_FDCWD, "/etc/passwd", O_RDONLY|O_CLOEXEC) = 3

Client Version: version.Info{Major:"1", Minor:"18", GitVersion:"v1.18.5", GitCommit:"e6503f8d8f769ace2f338794c914a96fc335df0f", GitTreeState:"clean", BuildDate:"2020-06-26T03:47:41Z", GoVersion:"go1.13.9", Compiler:"gc", Platform:"linux/amd64"}

Server Version: version.Info{Major:"1", Minor:"18", GitVersion:"v1.18.5", GitCommit:"e6503f8d8f769ace2f338794c914a96fc335df0f", GitTreeState:"clean", BuildDate:"2020-06-26T03:39:24Z", GoVersion:"go1.13.9", Compiler:"gc", Platform:"linux/amd64"}

+++ exited with 0 +++

myo@master-node:~$ kubectl cluster-info

Kubernetes master is running at https://192.168.1.132:6443

KubeDNS is running at https://192.168.1.132:6443/api/v1/namespaces/kube-system/services/kube-dns:dns/proxy

To further debug and diagnose cluster problems, use 'kubectl cluster-info dump'.

myo@master-node:~$

For second issue was with localhost:8080 was refused.

If you received the following error, "The connection to the server localhost:8080 was refused - did you specify the right host or port?"

Try the following command. 

mkdir -p $HOME/.kube

sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config

sudo chown $(id -u):$(id -g) $HOME/.kube/config