able to list, delete files, but unable to upload or download any file

Hi,

I'm using latest WinSCP 5.7.5 GUI and FTPs.
I can connect to my server, view, and delete files.
But when I try to copy any file, WinSCP fails with:

Timeout detected. (control connection)
Copying files from remote side failed.

I and my hosting provided (home.pl) suspect that control channel is working fine, but there is an issue negotiating encrypted data channel.

> 2015-08-24 20:35:29.355 STOR test.html
. 2015-08-24 20:35:29.366 Data connection opened
. 2015-08-24 20:35:44.299 Timeout detected. (control connection)
. 2015-08-24 20:35:44.299 Copying files to remote side failed.
. 2015-08-24 20:35:44.299 Got reply 1004 to the command 4
. 2015-08-24 20:35:44.299 Connection was lost, asking what to do.
. 2015-08-24 20:35:44.299 Asking user:
. 2015-08-24 20:35:44.299 Lost connection. ("Timeout detected. (control connection)","Copying files to remote side failed.")
* 2015-08-24 20:35:45.891 (ESshFatal) **Lost connection.**
* 2015-08-24 20:35:45.891 Timeout detected. (control connection)
* 2015-08-24 20:35:45.891 Copying files to remote side failed.

Love WinSCP, but as workaround I currently have to use other ftp client, which does not have this issue.

Please attach a full log file on Debug 2 log level showing the problem (using the latest version of WinSCP).