in WS_FTP, I have the choice to enable "FTP/SSL (AUTH SSL)" option. Thus, I can transfer in SSL mode.
In DOpus 10, I do not find this option. The only mode that will work on my server here is "Standard".
(Please note: I do have the SFTP addon installed.)
How can I activate SSL transfer on my server in DOpus?
Check in Help -> Licence Manager that it says FTP Advanced: Enabled, Never Expires.
If it does then you should have these options in the FTP connection drop-down:
Right, I do see all these options, and "FTP Advanced: Enabled, Never Expires" is active, too.
Prob is, neither of these options would connect me to my server - only "Standard".
And: It all works fine with WS_FTP, SmartFTP etc.
Why not with DOpus?
Compare the settings between the two programs. There must be a difference.
Also see what the ftp log on Opus says.
Log says "500 Illegal PORT Command".
A quick Google search for "500 Illegal PORT Command" finds a page that explains the error (a connection between the client and server is being blocked by a firewall or NAT or similar) and suggests turning on passive (PASV) mode (so the connection is created in a different way which works around firewall/NAT issues).
Toggling passive mode is also the first suggestion, and explained in more detail, in our own "FTP Doesn't Work" Opus FAQ.
If changing the passive setting does not help, check how WS_FTP is configured for the same site (as suggested before) and make sure Opus is set the same, and do so for all the other settings (e.g. port number, connection type, etc.).
"Passive mode" is the solution - thank you very much for your help!