ZM_MIN_STREAMING_PORT
Due to browsers only wanting to open 6 connections, if you have more than 6 monitors, you can have trouble viewing more than 6. This setting specified the beginning of a port range that will be used to contact ZM on. Each monitor will use this value plus the Monitor Id to stream content. So a value of 2000 here will cause a stream for Monitor 1 to hit port 2001. Please ensure that you configure apache appropriately to respond on these ports.