In order for Sync Meeting/Virtual Classroom that use WebRTC capabilities to function properly the following ports need to be accessible and not blocked by a firewall.
TCP Ports (open outgoing communication initiated from clients to *.youseeu.com servers):
UDP Ports (open outgoing communication initiated from clients to *.youseeu.com servers):
16384-65535 (the large space leaves room for larger numbers of concurrent meetings)
(open outgoing communication for external STUN server- used for NAT traversal and audio to stun.freeswitch.org servers - 18.104.22.168 and 22.214.171.124)
**Note: Please contact support if a specific set of IP addresses for YouSeeU servers is desired.**