Good afternoon Wilco and welcome back!
Thank you for reaching out to us.
We are sorry to hear about the reports showing a 404 error message.
I would love to help you with this topic.
I just went on the URL example you sent and it is definitely not broken.
However, in the screenshot you provided, I can see that the https://piek.international/organizer/piek-international-education-centre-i-e-c-gmbh/ URL has some extra things at the end (<a href…).
I am not sure where that specific URL is coming from (if you could tell me, it would help pinpoint the issue), but no doubt that this is an invalid URL structure.
Let me know how that goes.
Best regards,
Geoff B.