I have a brand new Remote Desktop Server running on a Windows 2012 R2 server. I followed the instructions on this site https://msfreaks.wordpress.com/2013/12/09/windows-2012-r2-remote-desktop-services-part-1/
to configure. So far it works great when I connect from a machine inside our network. I can connect with any user account. However, when I connect from a remote machine, whether on the internet or from a machine connected with the sonicwall VPN client, only the administrator can log in. I know that it is not a firewall issue because if it was, the administrator would not be able to log in either.
I have created a security group called RemoteDesktopUsers (without spaces to differentiate from the built in group) and made that group a member of the built in Remote Desktop Users. I have added the correct people to the group RemoteDesktopUsers. This allows them to log in from a local machine, but they still cannot log in from a remote machine. I have tried everything I can think of, and nothing seems to work. Any help will be greatly appreciated.