Freezing/stuttering video in Zoom and WebEx
Matthew Harrington 
My own use of WebEx is almost always without video, and we have no problem.
However, the pupil confined to the house, uses WebEx and Zoom to attend video classes, and experiences very frequent freezups, that last for multiple seconds.
Our Internet connection is through FiOS, with a 75Mbps limit in both directions. The clients of both of the video-conferencing applications run on the pupil's iPad -- via WiFi -- but the speedtests performed from the same device show low latency and high bandwidth (slightly exceeding the promised 75Mbps, actually).
According to the FiOS-provided router's own "Bandwidth Monitoring" page, the peak bandwidth use is only about 12Mbps...
An obvious suspect would be the teacher's own connection, but other kids in the same classes don't seem to complain...
What else can be the problem?
2 Answers
I recently stumbled upon a solution, but unfortunately it has to be done from the other end.
Videos are most commonly sent via screen-sharing, whereby the sender's screen is copied and sent over the internet. The more pixels in the screen, the more stuff has to be rendered. My PC, for example, was set up to display 1920 x 1080. I was sending out videos by screen-sharing, and before sharing my screen, I lowered my resolution to 1280 x 720. Everybody that received it said it came out much more smoothly than what they had seen from me before. This makes sense because I had 2/3 the number of pixels in each direction, thus 4/9 (less than half) the total amount of data that had to be sent out!
So if you can get your professor to lower his screen resolution, I think you're likely to have a much better experience.
Our problem was traced to a flaky WiFi-extender. Sometimes it worked fine, other times it staggered. This was hard to reproduce -- especially, because sometimes the Zoom-running device connected to the main WiFi directly resulting in near-perfect experience.
