UserAgent: Mozilla/5.0 (X11; CrOS x86_64 11151.11.0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/71.0.3578.21 Safari/537.36
Platform: 11151.11.0 (Official Build) beta-channel cave

Steps to reproduce the problem:
I cannot. Please watch the video as follows:
https://www.youtube.com/watch?v=qc-U9CUp3DI

What is the expected behavior?
The network in the school I am working is fine. Most of my colleagues uses ipad with airserver for windows without any problem. I use android tablet with 3 chromecast I own and they are working perfectly. However, my Chromebook (Asus C302 ) cannot work smoothly with Chromecast, mibox (an android tv box) and airserver for windows. Any mirroring action with Chromebook cannot last over 30 seconds under my school wifi network. The mirrored screen froze then but I can stop it in Chromebook. Those are weired.

What went wrong?
These days, I tried another chromebook (Acer R11) and encountered the same problem again. Chromecast with Chromebooks ran perfectly in my place. Today, I connected both chromebook and chromecast with my portable wifi router in my school. As expected, they were working fine.

In short, Chromebook mirroring cannot work under my school network with any devices. What can I do?

Did this work before? N/A 

Chrome version: 71.0.3578.21  Channel: beta
OS Version: 11151.11.0
Flash Version: