We have built a Windows server 2012 R2 RDS server, and setup the whole deployment on one server, Gateway, Broker, licensing, session host, and collection.
But when we go to shadow the user using Server manager or command line mstsc /shadow:n when get this very helpful error: Unspecified error in a Window called Shadow Error
I have tested Shadowing on another networks server with a similar setup and it works fine, only difference is the Active directory server are 2008 vs this one that doesn't work being 2003.
I have also tested using local accounts and still get the same error, and there is not a lot on the web regarding this error and RDS shadowing