If you configure your external loadbalancer to do a simple tcp pass-through to the api servers, and you do not use a DNS FQDN but just the ip, then you need to add the ip adress to the certificates too.
Example config:
```
## External LB example config
apiserver_loadbalancer_domain_name: "10.50.63.10"
loadbalancer_apiserver:
address: 10.50.63.10
port: 8383
```
Andreas Krüger