Error uploading image. Try again. IOS

Some photos do not want to be uploaded to the chat on my iPhone. I have my own server, everything works in a desktop application. Also, everything works on Tell me what could be the problem?

Switched to the appropriate category.

Do you have your site url set to the exact url which you access it at?

What file store do you have selected for file uploads?

What guide did you use to setup your server?