When Robo-FTP Server is running in "High Security Mode" it will refuse incoming connections from clients that are unable to use strong encryption algorithms like those required by Federal Information Processing Standards or the Payment Card industry. When High Security Mode is enabled, only connections encrypted with 256-bit AES are allowed.
To require High Security Mode on FTPS connections, open the Robo-FTP Server Console to the FTP Server menu and then mark the checkbox labeled "High Security FIPS Mode Encryption" on the SSL/TLS Options tab.
To require High Security Mode on SFTP connections, open the Robo-FTP Server Console to the SFTP Server menu and then mark the checkbox labeled "High Security Mode Encryption" on the General Settings tab.
