Registered attendee unable to join a meeting, and have attempted all troubleshoot suggestions

[Chrisidge]

Hi,
I am the host for meetings, for my company, and on some occasions, I have situations where an attendee cannot join a meeting as it's saying that the meeting passcode, they entered is incorrect, even though they are in fact entering the correct meeting code. I try to assist by suggesting all the following.
- Join via zoom app
- Join via browser
- join using meeting ID and passcode, instead of link and passcode
- join on another internet browser
- restart device and try again
I even try to cancel and re-register them on, but they still cannot enter.
They mention that they have join many Zoom meetings in the past, and never had issues. Unfortunately, they don't have another device to try join on, at the time of attempting to join the meeting.
At this point I have exhausted all options I know and had to sadly explain that they won't be able to join the meeting.
Are there any other options that can be tried?

Kind Regards