Video delay on specific accounts

Hi everyone,

I'm an online teacher and recently (since 3 days ago) I'm experiencing the following problem:

- My school's email account on zoom shows a delay of 10 seconds or so on video.
My audio is fine and on time, but video and screen sharing have this big delay. (which for lessons is a lot)

- My personal email account didn't show this problem on my tests. 

- Other online meeting services didn't show this problem on my tests. 

My wifi connection is fine. I have updated zoom. Even deleted and downloaded it again on my MacBook pro. 

Does anyone have any idea what could be done?