Remote Desktop from Windows

I have been trying for some time to properly allow for Remote Desktop via Windows to connect to my Mac Mini from any where I have a Windows PC and an Internet connection. I successfully have VNC from my Mac when I am traveling, but I do not have it properly setup for a Windows Remote Desktop session. I have tried to port forward the RDP port and tried to select the "VNC Viewers may control screen with password" in Settings > Sharing > Screen Sharing > Computer Settings, however no luck.

Does any one have a definitive way to get this working? Yes, I know RealVNC or another application would be suitable, but the capability - as far as I have read - is there and built in. Just does not function. Additionally, I do not want to have to install RealVNC on any Windows machine I go to and want to VNC back into my Mac.

Thanks ahead of time.