Further investigation may show the Application Event Log Error code 3734:
"An error occurred returning the list of user technologies. Check the web.config settings.
The underlying connection was closed: An unexpected error occurred on a receive."
This error has been found to occur on servers which are configured to use SSL and have the Windows Security Update KB3042058 installed.
Winfrasoft are looking into this issue and are working on a solution to the problem. If you are experiencing this error, as a workaround you can either:
(1) Uninstall KB3042058 from the server.
(2) Enable the HTTP binding IIS (SSL can remain) as follows:
In IIS, Add back the standard HTTP binding on port 14000.
Edit the C:\Program Files\Winfrasoft AuthCentral\wwwroot\web.config file and set the AuthCentralServerPort = 14000 and EnableSSLwithAuthCentralServer = False.
For further information see the Microsoft KB site: https://support.microsoft.com/en-gb/kb/3042058