I installed RD Gateway on my RDS server (2008 R2), which installed Network Policy Server as well. After installing, I could no longer connect via Remote Desktop from any machine on the network to one particular server running Server 2003 R2. I get this error:
"The remote computer requires that authentication be enabled to connect. The connection cannot proceed because authentication is not enabled."
Nothing was changed on the 2003 machine, and it doesn't have these options. I've removed the RD Gateway and Network Policy Server, but the problem remains. No other machines are affected. Again, I changed nothing on the 2003 server, and I've been connecting to it just fine for years, right up until I installed RD Gateway.