I have a 2012 Macbook Pro and a 2013 Mac Mini, both running El Capitan with all latest updates. The Mac Mini is "headless" as I use it as a media server. I connect to the Mini from the MBP using the screen share facility from within Finder in Mac OSX.
However I find the screen sharing option to be very unreliable. I would say there is a 50/50 chance that the "Screen Share" button will be missing in Finder when I go to use it. Sometimes it reappears after a minute or two. Sometimes not at all - in these cases I have to plug in a monitor, mouse and keyboard to reboot the Mini.
Does anyone know how to make it work reliably or can suggest a better and more stable alternative.