Are you using Node or PHP? I know Apache for PHP has a max upload filesize in the php,ini file. Maybe your original is too large? If you try with a smaller source does it upload fine?
Just read your post closer.
It is my bet you are exceeding the server file upload limit as I suggested. If you are using PHP it is an easy fix. By default apache sets max file upload to 2MB. You can adjust that in the .htaccess file.
## Start Max File Upload Size
php_value upload_max_filesize 10M
php_value post_max_size 11M
I looked up the method for Node on ChatGPT but it was way over my head.