screen sharing stopped working
I'm running Sierra on my MacBook Air and running El Capitan on two Mac Minis that are 6 and 7 years old. After the last OS security update (April 2018), screen sharing has stopped working. The file sharing is working perfectly. Rebooting and firewall changes do not fix the problem. I have Remote Management turned on the two Minis. Screen sharing does not work between the two Minis either so I've ruled out OS mismatch as the source of the problem.
VIN,Mac mini (Mid 2010), OS X El Capitan (10.11.6)