I just recently did something like this. I'm pretty new at it so I'm not well educated on how it all works, but under preferences in the desktop menu, there's a setting called remote desktop. You may need to change some of these settings.
For me, I had to connect remotely using port 5801 and then when the pop-up appeared with the ip, port, and display number, I entered '0'. This also means that I had to open port 5801 in addition on my system and in my router.
This is all accessed with a desktop already running. Just something you might want to try.