We are able to connect using the FTP details thorugh filezilla but while trying to directory listinging it stuck and giving the error in server logs.

“Sorry, cleartext sessions are not accepted on this server. Please reconnect using SSL/TLS security mechanisms”:

In order to resolve check below steps.

The problem due to some ftp client not support the “TLS Encryption Support” so we need to change the ftp configuration.
1) Go to whm >> Service Configuration >> FTP Server Configuration
2) Set “TLS Encryption Support” as “optional”
3) Click on “save” button
4) Done