How to establish VNC connection to LightDM?

I'm looking to do a remote connection to a Ubuntu 16.04 machine through VNC. I'm using Remmina on client-side and I'm able to connect easily after the LightDM login, but I'm unable to perform the login on server-side remotely from the client.

I tried following different guides, but I ever get something like: 'unable to connect'. I need to leave the Ubuntu 16.04 machine headless, so turn it on and perform the login remotely from another machine. How could I do that?

Thanks in advance for answers.