Problems accessing the Zoom servers

Hello,

On September 18, we organized a Zoom Webinar for one of our clients, but we experienced trouble connecting to the Zoom servers.

The client has a strict firewall policy and needs to know which ports to open before we can access Zoom. Could someone please provide a list of the ports that need to be opened in the firewall, and clarify whether there is any difference between the port numbers for a free Zoom Meeting and a paid Zoom Webinar session?

Kind regards,
Remco