Unable to get Realms

New User GUIs may report the following error: "Unable to get realms from REDDOXX Appliance."

The new user interfaces communicate via https, this error occurs when there is no virtual host entry set in the appliance.

Add a new HTTP/S Virtual Host Entry in Admin Webinterface => Configuration.
This requires a SSL Certificate that can be either the REDDOXX dummy certificate, a own certificate or an automatically created lets encrypt Certificate.