Problem solved. Before installing malwarebytes, I had shut down the VNC server on both machines. When I rebooted the servers did not start up again. Manually restarted them. Working now. Thanks for the info that malwarebytes and VNC play well together -- that caused me to look elsewhere for the soruec of the problem.
I use VNC to make connections to another computer on my home network. After putting Malwarebytes Pro on both computers, neither one can make a VNC connection to the other. How can I prevent Malwarebytes from blocking the ports that VNC uses? Thanks in advance for any suggestions.