I have a MacBook Pro and a Mac mini, both running Mountain Lion. This problem, however, started when I had Lion. I can remote in to my MacBook Pro just fine from my iPhone and iPad. But I can't remote into my Mac mini. It started out just fine and I could remote into the Mac mini from my iPhone, iPad as well as my MacBook Pro. Later (I was still on Lion), I could still log in from my iDevices but no longer could from my MacBook Pro. This behavior continued after installing Mountain Lion. Now, I can't remote in from anywhere. I want to avoid doing a clean install, but I will I have to.
I have tried switching from Remote Management under Sharing to Screen Sharing, and back. nothing works. Recently (before I lost the ability to remote in at all, but after I lost the ability to remote in from my MacBook), I also lost the ability to edit my parental controls on the Mac mini from my MacBook. Little by little, I am completely losing the ability to remote in/screen share to my Mac mini at all. Currently, I can only remote in via SSH for a terminal.
My network includes my AirPort Extreme, Time Capsule, MacBook Pro (mid-2010), Mac mini (mid 2010), iPad (3), iPhone 4S, and my father's PC. Only my father's PC is connected by wire. The rest is wireless.
If anyone can guide me in the right direction, I'll be very grateful.