Can't open data connection

[habla5000]

Hello to everybody

Since a couple of days I have a problem to download files from a FTP-Server. Neither me nor the administrator of the remote FTP server are aware of any changes made on the configuration.

Version:
BestSync 2012
Deutsche Version Ver7.0.1.9(64Bit)
Premium Lizenz

Configuration:
Port 21
passive mode not activated

Log:
>CWD /users
<550 /users: folder not found
>MKD /users
<550 directory exists
Can not detect server's timezone, use local timezone (-60) minutes.
/users/miller/
>DELE /users/miller/
<450 deletion failed
End detect server functions.
>PORT 192,168,4,100,23,202
<200 command successful
>MLSD /users/miller
<425 Can't open data connection.

What is the problem, why the connection can't be opened?
It looks like a problem with a firewall but as nobody did any change?! Which ports must be open?

Thank you very much for your support!
Kind regards, habla5000

[RiseFly]

This problem may be releated to the firewall setting.
If you have not use the passive mode, you'd better to set the port range used by the active mode. Following thees step:
1. Click "Option"/"Option" menu, show the "Option" dialog box, in "FTP Active Mode" setting page, check "Limit local ports used by BestSync", and specify a range of port numbers.
2. Add these port to the except list of Firewall Software.

[habla5000]

Thank you very much for your assistance! I don't know why it worked before, but now I did what you have suggested and it works!
Kind regards, habla5000

[Louiseravot]

Hi! Your FTP connection issues with BestSync 2012 seem related to firewall or network settings blocking the data connection (port 20 or a dynamic port for passive mode). Since passive mode is off, the server tries to open a data connection back to your client via the PORT command, which may be blocked. To fix this, either enable passive mode or ensure your firewall allows incoming connections on the data ports. For detailed information on network regions and codes, tools like [URL=https://www.geopostcodes.com/]postal code lookup services[/URL] can also help in configuring access based on location. Check that ports 20 and 21 plus the data port range are open on both sides.