I had Windows Server 2012 R2 with Essentials Experience role installed and working just fine, and was able to use Remote Desktop to access the server and some connected PCs from the Internet. I then attempted to install Exchange 2013 on the same server and many things broke, including RDP. So I uninstalled Exchange, but that didn't resolve the RDP problem. So I attempted to create a Hyper-V VM on the server, only to discover that Essentials Experience and Hyper-V roles don't play nicely together (VMs constantly going into Critical states). So eventually I removed Essentials Experience from the physical server, created a new VM and installed Windows Server 2012 R2 on it and added the Essentials Experience role.
So now I have a physical server running WS2012R2 running the Hyper-V role, and a VM, created from scratch, running WS2012R2 with the Essentials Experience role. I don't have Exchange installed anywhere. Everything is working great, except somehow the RDP problem persists. Some setting in Active Directory perhaps; it's the only thing I can thing would have survived the creation of new VM. When I attempt to Remote Desktop to the Essentials server, I get a Windows Security dialog saying: RD Gateway Server Credentials Type your user name and password to connect to <mydomainname>. The logon attempt failed.
Every attempt to enter credentials fails, whether I prefix the username with the domain name or not. I know the credentials are correct, and I am trying two different usernames, one of which is the domain administrator.
I don't know if this is relevant, but following advice on loosely-related posts, I tried to browse to <a href="https:///rpc">https://<mydomainname>/rpc. This asks for credentials three times and then dispays a blank page with the text"Access Denied". I haven't installed Terminal Services Gateway Manager as yet another post said it shouldn't be used to manage Essentials.
What should I do to try to resolve this? I've tried the Repair wizards within the Essentials Dashboard, without success.