Error accessing Hub API - HTTP 599: SSL certificate problem

(discussion from https://github.com/jupyterhub/binderhub/issues/1140)

You can check the summary of my issue here : https://github.com/jupyterhub/binderhub/issues/1140#issue-678602668

This is not related to the following topic because I stopped using opennebula k8s service:

UPDATE:
When we spawned the cluster, our binderhub domain was not accessible from within the LAN (SSL certificate problem). After adding the line <external-IP> <binder-domain> to /etc/hosts, the domain is accessible on our server.
Sadly, when I ssh into the binder pod, the hub API is still not accessible. Any thoughts ?
(just a remainder that I am able to connect externally to the binderhub domain through https).