This is what the iis documentation says:
5xx - Permanent Negative Completion Reply
The command was not successful, and the error is permanent. If the client retries the command, it receives the same error.
⢠500 Syntax error, command unrecognized. This may include errors such as command line too long.
⢠501 Syntax error in parameters or arguments.
So i think you should use some other ftp server to get this job done. I can recommend serv-u ftp server when you're not that skilled, or ioftpd/g6ftpd when you're a bit more advanced
.