Meeting ID not valid--but only for some attendees

[janekat_]

Yesterday and the previous time I hosted a meeting, some of my attendees got back to me saying that they couldn't enter because they were getting a message the meeting ID was invalid. But there were many people there, so it was not a universal issue. 

I usually use a waiting room but didn't this time as I knew some people would join late, so perhaps that's why I haven't encountered this before.

Is there anything I can suggest people do ahead of the next meeting to solve this issue? I'm hosting the same event today! 

I found a post on this issue from 3 years ago. Hopefully it isn't still just a standing issue with zoom that meeting IDs only work sometimes?? (FYI I double checked the ID they were sent and the ID they were using; it was correct).