K3s:

Access K3s from outside cluster.

Make a hole in the UFW firewall for 6443.

Then take this config:

sudo cat /etc/rancher/k3s/k3s.yaml
apiVersion: v1
clusters:
- cluster:
    certificate-authority-data: 
    REDACTED
    server: https://127.0.0.1:6443

And change 127.0.0.1 to the actual IP of your server.

Then drop this in :

~/.kube/config

And run

kubectl get pods -A

You are now connected to k3s from outside.