Product:
Cognos Controller 10.2.5130.56
Microsoft Windows 2012 R2 standard Server
Microsoft SQL 2008 R2 database Server 10.50.4000.0

Problem:
One user cannot login in to Cognos Controller over VPN connection.
Single Sign On is active with use of CAM users. After select the database to use the error message appears.

Error message:
An error occurred while trying to access the server
Invalid URI: The hostname could not be parsed.

Solution:
Change Cognos Controller Configuration to use FQDN instead of only hostname in all places.
Special at Client Distribution Server configuration, ensure that CASURL and WSSURL point to
http://servername.domain.com/ibmcognos/controllerserver
instead of only servername.

Ensure that in Cognos BI Configuration Environment, that all references to localhost is replaced with the FQDN name of the servers.

Also on server and client ensure that server is part of local intranet.
Go to Windows Control panel.
Go to Internet Options.
Select Security tab.
Click on local Intranet.
Click on Sites button.
Click on Advance button.
Enter the *.domain.com ( the company domain ) to the “add this website to the zone:” and click ADD button.
Now the server name or the last part of FQDN should show in the list of websites for Local Intranet.
Click OK to leave Internet Options.
Restart IE and try to surf to http://servername.domain.com/ibmcognos
– If it works without login message, then it is correct setup.

More information:
http://www-01.ibm.com/support/docview.wss?uid=swg21366724