Join Site to an ArcGIS site that only allows HTTPS connections fails with the error: Unable to connect. Please verify that the ArcGIS Server site URL you entered is correct.
To add a new node to a running ArcGIS Site that has SSL enabled:1. Close the create site wizard on the current machine.2. Connect to the existing ArcGIS Site: http://[site]:6080/arcgis/manager.3. Log in as the Primary Site Administrator and click Site > Machines > Add Machine.4. Enter the machine name and URL(http) to join the new machine to this site.