Кстати про Zoom. Он так от ни разу не TCP, у него есть фейловер в TCP, это да:
Media Routing. With a successful connection to the optimum Zoom Multimedia Router for the session, the Zoom Client prioritizes creating a connection for each type of media that will be exchanged such as video, audio, and content. Each of these media connections attempt to use Zoom’s own protocol and connect via UDP on port 8801. If that connection can not be established, Zoom will also try connecting using TCP on port 8801, followed by SSL (port 443). By leveraging different connections for each type of media, further network optimization technology can be applied such as DSCP marking to ensure the most important media is expedited through the network.