Remote App Resource Feed via IP Address Not Opening From MAC

Problem:
MS Remote Desktop is installed on a MAC. You've got a server set up to provision Remote Apps. You can connect to the server via the 'Desktops' tab but trying to access the Remote Apps is a different story. You can enter the resource feed,

https://192.168.0.100/RDWeb/Feed/webfeed.aspx

and you can enter your username/password details to make the app appear well enough in the App list....but when you come to open it, it kicks back with a 'Unable to connect to remote PC. Please Verify Remote is enabled, the remote PC is turned on and Available on the network, and then try again' error.

This is a little confusing since you've been able to talk to the server to get the app to show but no, apparently, you can't run the app because the server has vanished. 

Fix:
As counter intuitive as it may seem, the fix is to use the FQDN and edit the host file on the mac to resolve the fqdn to the server's ip address. 

So on the client mac edit the host file (open the Terminal and enter 'sudo nano /etc/hosts') and add in an entry for your server and the ip address. Then change the resource feed url to use the FQDN:

https://myserver.mydomain.local/RDWeb/Feed/webfeed.aspx

Try opening the app now and you should find it works.