Thanks for your help @LeonidS

The thing is I need to publish the CERT of my custom domain somewhere on the UNA Cloud instance. But this part is not documented.

So when I try to activate https, the service does not work and UNA is not reachable.

I need to find the process to publish my custom domain CERT on UNA Cloud before activating HTTPS in the settings.

Am I right?

Thanks for your help :)