File uploader with FTP functionality

So I have a client for whom I’m currently starting up a new WordPress site. One of his requests is the ability to have his clients upload files from frontend with a very simple interface. The website is on a hosted webserver, but he would like to have all the uploaded files sent to his own Synology NAS server which resides in his office.

Does anyone have a suggestion on how to achieve this?

I have been searching for a plugin with FTP functionality but to no avail.

It could also be an embedded FTP interface, but there has to be a way to submit files alongside his clients name, email, message, etc.

I would greatly appreciate any suggestions. Thanks.

/emenick