Active FTP issues with TLS/SSL

Corey716

I'm having problems where an Active FTP session using TLS/SSL Explicit encryption is not able to list directories once connected. I can sign in where the initial handshake works just find. However, when the command is sent to obtain a directory (MLSD) takes place, I get the error "Unable to establish SSL connection (CLIENT ERROR: Client may have rejected the SSL certificate. Ensure the SSL certificate has been issued by a certificate authority.)" followed by "426 Data connection closed, SSL / TLS negotiation failed." This only is a problem when the client is on the WAN. Clients on the LAN do not have a problem. The FTP server resides on the DMZ.