Connecting to Collabora Online Server: Could not establish connection to the Collabora Online server

@wwe Thanks again
Currently, am not even able to access the admin panel, at least that should work first right?
I am trying to access the admin panel through this URL https://mydomain:9980/browser/dist/admin/admin.html before proceeding to another staff am I right on the URL?

I am just thinking that Coolwsd is requiring path to public and private key, is there any config file in addtion to coolwsd.xml where I might deal with SSL? Because the error seems related to SSL, both from browser log and coolwsd.service