If your PC is behind a firewall, you may need to open certain ports for any PC using ezFMD, so that the software can contact the NMVO and update your log files. Typically, this is done by someone familiar with the technical aspects of your network.
For those planning to install ezFMD behind a more comprehensive firewall, download the detailed document listing all the endpoints which are required from the Downloads page. (This guide has been updated 01/Nov/2019 to reflect the changes made by several NMVOs, including the IMVO.)
A good article on managing firewall ports in Windows can be found at this (external, Microsoft) link.
Background: A firewall is a network security device that monitors traffic to or from your network. It allows or blocks traffic based on a defined set of security rules.