SQL Server 2012 Reporting Services: "Unable to connect to the remote server"
I had a similar problem when installing SSRS for a SCOM installation.  It was configured with SSL but when I removed this I started getting the same error as above. Solution was to change the SecureConnectionLevel in rsreportserver.config to 0.

https://connect.microsoft.com/SQLServer/feedback/details/686214/removing-ssl-cert-in-config-manager-doesnt-properly-modify-rsreportserver-config