Networks are such a stack relying on many many things working together to get the end result you’re after.
To increase the maximum size of a form uploaded file in PHP you need to increase both the upload_max_filesize AND the post_max_size. The post_max_size isn’t always the most obvious, but comes into play when the file gets sent to upload via a form (HTTP POST)
/etc/php/php.ini post_max_size to big enough or set to zero (0) for unlimited
/etc/php/php.ini upload_max_filesize to big enough