Access kubernetes cluster outside of VPN - kubernetes

Question

I configured a kubernetes cluster with rke on premise (for now single node - control plane, worker and etcd).
The VM which I launched the cluster on is inside a VPN.
After succesfully initializng the cluster, I managed to access the cluster with kubectl from inside the VPN.
I tried to access the cluster outside of the VPN so I updated the kubeconfig file and changed the followings:
server: https://<the VM IP> to be server: https://<the external IP>.
I also exposed port 6443.
When trying to access the cluster I get the following error:
E0912 16:23:39 proxy_server.go:147] Error while proxying request: x509: certificate is valid for <the VM IP>, 127.0.0.1, 10.43.0.1, not <the external IP>
My question is, how can I add the external IP to the certificate so I will be able to access the cluster with kubectl outside of the VPN.
The rke configuration yml.
# config.yml
nodes:
- address: <VM IP>
hostname_override: control-plane-telemesser
role: [controlplane, etcd, worker]
user: motti
ssh_key_path: /home/<USR>/.ssh/id_rsa
ssh_key_path: /home/<USR>/.ssh/id_rsa
cluster_name: my-cluster
ignore_docker_version: false
kubernetes_version:
services:
etcd:
backup_config:
interval_hours: 12
retention: 6
snapshot: true
creation: 6h
retention: 24h
kube-api:
service_cluster_ip_range: 10.43.0.0/16
service_node_port_range: 30000-32767
pod_security_policy: false
kube-controller:
cluster_cidr: 10.42.0.0/16
service_cluster_ip_range: 10.43.0.0/16
kubelet:
cluster_domain: cluster.local
cluster_dns_server: 10.43.0.10
fail_swap_on: false
extra_args:
max-pods: 110
network:
plugin: flannel
options:
flannel_backend_type: vxlan
dns:
provider: coredns
authentication:
strategy: x509
authorization:
mode: rbac
ingress:
provider: nginx
options:
use-forwarded-headers: "true"
monitoring:
provider: metrics-server
Thanks,

Answer 1

So I found the solution for RKE cluster configuration.
You to add sans to the the cluster.yml file at the authentication section:
authentication:
strategy: x509
sans:
- "10.18.160.10"
After you saved the file just run rke up again and it will update the cluster.