I’ve been modifying the configuration on a Windows Server 2008 R2 application server to use Remote Desktop Gateway and a SSL certificate, instead of raw RDP over port 3389.

After installing the RD Gateway, RD Web Access and IIS role services, and configuring everything correctly (or so I thought), my remote apps still would not work. Launching from the RDweb page or using a RemoteApp RDP file started well, but after successful authentication and then the warning about launching applications from remote sources,  there was a long pause, then this:

“Remote Desktop can't find the computer ... this might mean that .... does not belong to the specified network. Verify the computer name and domain that you are trying to connect to.”

Because the address was resolving fine externally, I added it to the hosts file on the application server (which is not on a domain by the way), as follows:

127.0.0.1     cmsi-demo.esdm.co.uk

… and everything worked nicely.

Why I needed to add this to the hosts file this time, and not on any of our other application servers, I do not know. Answers on a postcard please?