Why is the timestamp of uploaded/downloaded file different from the timestamp of source file?

There are two possible reasons:

• You have not checked Preserve timestamp transfer option (see Transfer options dialog or transfer tab of Preferences dialog)
• WinSCP and the server interpret timestamp differently.

If the latter is true there are two options that you can set in WinSCP to try to make it interpret timestamp in the same manner as your server.

• Option Dayling saving time is usefull when timestamp of some files if shifted by one hour
• Option Server timezome offset (SCP protocol only) is usefull when timestamp of all files is shifted by the same time span.
• You may need to combine both options in some cases.

Dayling saving time option is located on Environment tab of Login dialog. Some servers (mostly on Windows) adjust file timestamp with start of DST and some not (Unix). The option select between the two approaches. For backward compatibility, Windows-style approach (server does adjustment) is selected by default, while the Unix-style is probably the correct one. Note that the this option must be set correctly before transferring the files. It does not make sense to try to use it to adjust the timestamp of already transfered file.

If you use SCP protocol, there is the second option for you to try, Server timezome offset on SCP tab of Login dialog. It defines difference between the server time zone to the local timezone. For example if the timestamps of remote files are two hours ahead of local files, set the option to -2 hours.

Once you set your preferences, save them to stored session.