linux – The logs stopped on the FTP server

I have an FTP server that is receiving Cisco-WSA records, but suddenly the records stopped,

  • Checked that the vsftpd service is running and restarted it in multiple
    sometimes too
  • Telnet checked on the ftp server on port 21 is open and
    be connected
  • Connection checked using sftp with the same user.
    as in cisco-wsa the connection was successful.
  • Port 21 is open.

What can be the problem here?
Also when I did it "netstat -an | grep ftp I see all connections between my ftp server to wsa in WAIT TIME State, can this be the problem? How can i fix this?