That's probably a PHP configuration issue on the server
IIRC, you need to change 2 PHP.ini lines relating to max memory and max file upload (though I don't recall the KV pair name at the moment)
February 07, 2020 at 02:13PM
via reddit https://www.reddit.com/r/NextCloud/comments/f0evbj/ios_app_upload_file_size_limits/fgtcwyi?utm_source=ifttt