Zoom link doesn't work

[VVAO]

I had a Zoom meeting yesterday evening, and set up a Zoom-link. The first participants (about 10) had no problem with the link and could easily join the meeting, but the rest did not. When they tried to join the zoom-meeting they received an error '502 Bad Gateway'. This was very frustrating, because therefor a lot of participants couldn't join the meeting. We also were not able to solve the problem, because we didn't know what the problem was. 

Can anyone (from the Zoom-team of another expert) tell me what could cause this problem and what we should do next time to prevent this?