Please don’t run more ftp servers. Ftp is eol. Use something more modern
Totally agree. There was a time when FTP had some advantages over the then-standard HTTP when distributing large files. That time is decades in the past.
If you want to mostly distribute data, https is a better choice.
If you trust your users and want them to send and receive data, SCP or SFTP (over SSH) is a better choice.
I had a conversation a couple of years ago with one of the authors of the FTP RFC (which I discovered, to my embarassment, at the end…) in which he expressed dismay that anyone is still using it.
I have had good luck moving users to S3. No disk size limits and there are free GUI clients for Windows and Mac. I just told them the new credentials and never got any complaints after that.