Pages returning 404 error for some users only

Hello there.
I am providing this page (please ignore the topic it’s on), but only for some users, it’s not working. However, for other users, it works?

How can I fix it? How can they help me debug the page to make it availiable? It is annoying to share a page and not being able to open it.

One of the users opened it in Safari, iOS 10.0.2

Thank you~

What do the users who can’t see the page see instead? Are they redirected to the 404 page on Or do they see a different page?

They go to the infinityfree 404 page