ION: FTP in File Connector is not working. What kind adapter does ION 12.0 is using for FTP?

We are getting below error when trying ftp connection from ION:

Message: Adapter test connection failed: java.lang.Exception: Unable to validate the connection for hostName '1XX.XX.XXX.XXX'. Cause: FTP server 16x.xx.xx.xx0 refused login for user EAZXXXXX. ReplyCode "500"