Istio gateway not listening when using explicit ftp over ssl

1
  1. Installed customised IstioOperator, ingressGateways with aws internal nlb. Added port: 21, protocol: tcp, targetPort: 5021 in IstioOperator gateway yaml.
  2. Created Kind:Gateway, with port:5021, protocol: TLS, tls mode: MUTUAL
  3. Created Kind: VirtualService, using spec tcp: match port: 5021, route destination, port:5021, with host.

It is working fine if I use below implicit ftps using curl command, note here I am using ftps

curl -kG --ftp-method nocwd --cert "/home/SelfSignedCert/Client1/client1.crt" --key "/home/SelfSignedCert/Client1/client1.key"  -u testftpuser:password ftps://abcftp.dev-xyz.com:21

It is NOT working when using explicit ftp curl command as mentioned below

curl -kG --ftp-method nocwd --ftp-ssl --cert "/home/SelfSignedCert/Client1/client1.crt" --key "/home/SelfSignedCert/Client1/client1.key"  -u testftpuser:password ftp://abcftp.dev-xyz.com:21

Can anyone suggest how I can achieve explicit way when using ftp.