One of my student has a strange bug. If we use one of three free boards, and he writes anything, I just don’t have it on my board. I can see his mouse, his movements but when his mouse stops and he claims that he finished the phrase, it never loads. I asked him to type, the situation was the same. But his screens prove that at his place there are writings and typed words. 

What could it be? What can I do about it?