Unable to connect to the remote server error using ROPC with C#


I’m having some issues using ROPC approach with C#. I have an application where I’m using ROPC approach since some months and suddenly it has stopped to work in one machine. In another machine everything works correctly. I get the error “Unable to connect to the remote server”. As I said, with the same application in another machine with the same user eveything works, but I don’t know what is happening with the other machine. Any idea about a possible reason?