Firewall port: 16384/32767

Q:Why does the port range 16384-32767 (RTP media) need to be opened up for Moodle/Meeting sever?

A:

This port range only needs to be opened for outbound connections. BigBuleButton needs access to all of the ports in this range to ensure that the number of possible simultaneous media streams is sufficient. If these ports are not open for outbound connections, then any media that uses RTP may be intermittent or completely unavailable.

RTP can carry any data with real-time characteristics, such as interactive audio and video.

RTP

The Real-time Transport Protocol (or RTP) defines a standardized packet format for delivering audio and video over the Internet. It was developed by the Audio-Video Transport Working Group of the IETF and first published in 1996 as RFC 1889 which was obsoleted in 2003 by RFC 3550.

Port

RTP does not have a standard TCP or UDP port that it communicates on. The only standard that it obeys is that UDP communications are done via an even port and the next higher odd port is used for RTP Control Protocol (RTCP) communications. 

Although there are no standards assigned, RTP is generally configured to use ports 16384-32767.

see Are there specific ports assigned to RTP?(http://www.cs.columbia.edu/~hgs/rtp/faq.html#ports)