Screen sharing in OSX El Capitan 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.
I use a standard VNC client. Once you have Screen Sharing enabled on the System Preferences you can access your remote Mac with any VNC viewer/client application.

More precisely, on my Mac I use the outdated Chicken (still working fine on El Capitan, though) and for the iPhone/iPad there are also plenty of choices on the App Store.

NOTE: Make sure that you set a password on the Screen Sharing preferences.