Winscp 5.9.3 "failed to retrieve directory listing" FTPS implicit port 990

Been kicking my head this pass 2 weeks trying to figure out what is wrong, am really desperate and need some help, when I test the connection from inside my org it works flawlessly, but when I test it from outside it return me this error:

Status: Connecting to 172.16.4.17:990...
Status: Connection established, initializing TLS...
Status: Verifying certificate...
Status: TLS connection established, waiting for welcome message...
Status: Logged in
Status: Retrieving directory listing...
Command: PWD
Response: 257 "/CECC" is current directory.
Command: TYPE I
Response: 200 Type set to I.
Command: PORT 172,16,4,251,8,50
Response: 200 PORT command successful.
Command: LIST
Response: 150 Opening BINARY mode data connection.
Response: 550
Error: Failed to retrieve directory listing

firewall ports 21/990/22 are open and it works using port 21 (sometimes), but cant get it to work with port 990, how can you help?
........

This does not look like WinSCP log.
Anyway, why do you use the active mode? Try the passive mode (that's the default in WinSCP).
https://winscp.net/eng/docs/ui_login_connection
https://winscp.net/eng/docs/ftp_modes

martin wrote:

This does not look like WinSCP log.
Anyway, why do you use the active mode? Try the passive mode (that's the default in WinSCP).
https://winscp.net/eng/docs/ui_login_connection
https://winscp.net/eng/docs/ftp_modes

Well I wanna have a FTPS connection using port 990.ALready have my server configured with implicit connection 990.
Passive mode is with port 21 and it doesn't encrypt password nor the data being transfered, how can I connect on my FTPS having port 990 open with WinSCP??? Because it always return the "failed to retrieve directory listing' error. Yes, I can connect with port 21 but its not secure, how can you help please, any advice or suggestion will be more than welcome, unless i configured badly my FTPS......

Looking forward on reading from you, thank you....

Passive mode is with port 21 and it doesn't encrypt password nor the data being transfered

That's complete nonsense. The passive/active mode has nothing to do with the encryption. You can have any combination of the active/passive and the unecrypted/explicit encrypted/implicit encrypted.

martin wrote:

Passive mode is with port 21 and it doesn't encrypt password nor the data being transfered

That's complete nonsense. The passive/active mode has nothing to do with the encryption. You can have any combination of the active/passive and the unecrypted/explicit encrypted/implicit encrypted.

I agree, I got it all messed up, and i tough passive was accesing it thru port 21, so I've put it on passive mode and tried to still get conected thru port 990 but still give me the same error,any other advise? do u think its A SETTING ON MY FTPS the problem? because i can access it easily on port 21

You cannot get the same error with the passive mode.

Show us WinSCP log file.

martin wrote:

You cannot get the same error with the passive mode.

Show us WinSCP log file.

Appreciate and am very thankful for you taking the time to help me with this issue, am sending you the log, take a look at it and tell me what you think and see, thanks and waiting on your reply.

You have probably not enabled the data port rules in Windows firewall.
Or if you have some NAT between you and the server, you also need to route the data ports. Not only the 21/990 ports.

https://winscp.net/eng/docs/guide_windows_ftps_server#window_firewall
https://winscp.net/eng/docs/guide_windows_ftps_server#firewall

martin wrote:

You have probably not enabled the data port rules in Windows firewall.
Or if you have some NAT between you and the server, you also need to route the data ports. Not only the 21/990 ports.

https://winscp.net/eng/docs/guide_windows_ftps_server#window_firewall
https://winscp.net/eng/docs/guide_windows_ftps_server#firewall

So heres the situation, I've follow ur step for creating a FTP server on iis7 using port 990, port range are from 2000 to 65535, External Ip adddres of firewall is the static IP on the FTP server(172.16.1.17), in the inside I can access it with port 990, but from the outside we did a mapping 172.16.4.17 and the users can't access it by using port 990, only with port 21 can they have access. In bindind i put the IP address of the server ......1.17.
WHere did I go wrong, its weird that I can access it on the inside but not the outside.
Firewall Server is OFF, firewall enterprise have port 21,990 open, I've test it with all port open but I still get the "failed to retrieve directory listing"
What do you think? am out of ideas.

Anonymous wrote:

martin wrote:

You have probably not enabled the data port rules in Windows firewall.
Or if you have some NAT between you and the server, you also need to route the data ports. Not only the 21/990 ports.

https://winscp.net/eng/docs/guide_windows_ftps_server#window_firewall
https://winscp.net/eng/docs/guide_windows_ftps_server#firewall

So heres the situation, I've follow ur step for creating a FTP server on iis7 using port 990, port range are from 2000 to 65535, External Ip adddres of firewall is the static IP on the FTP server(172.16.1.17), in the inside I can access it with port 990, but from the outside we did a mapping 172.16.4.17 and the users can't access it by using port 990, only with port 21 can they have access. In bindind i put the IP address of the server ......1.17.
WHere did I go wrong, its weird that I can access it on the inside but not the outside.
Firewall Server is OFF, firewall enterprise have port 21,990 open, I've test it with all port open but I still get the "failed to retrieve directory listing"
What do you think? am out of ideas.

Ok now i get "faled to retrieve directory /cecc" but i get connected, but i cant transfert files or do anything on it, sometimes

You should ask for further help on a appropriate site. Like superuser.com.
This is a support forum for WinSCP, not a general topic forum.

Thank a lot for ur help, may God keep on blessing you, appreciate