Unable to add RDS Session host server back into collection.

[Bob_from_Reno]

Hi, I have a remote Desktop deployment on Server 22, I removed a session host server as I was having some issues and when this was resolved I was unable to add the Server back to the collection. It keeps telling me the Server needs to be domain joined. The server is domain joined. I unjoined it from the domain , re added it. changed the server name, checked DNS and can not work out why this is happening. There are 4 servers, 2 are brokers and 2 are meant to be session host servers. 

[#2]

As an update I have had people go through this who are Microsoft Certified and have many years of experience. No forums reveal anything close to the answer and when trying to get support from Microsoft they would not talk to us. They would not even let us pay them. Microsoft are a threat to continuity because if their software breaks it stays broken.

I am building a new RDS Session Host Server.

I hope Microsoft read these comments.