I suggest several possibilities:
1) It is possible the web server is in a different time zone from you; that
would possibly account for the difference because the time on the remote
server is not your local time, it is the time of that particular time zone
the server is located in .
2) It could be that the "timestamp" is actually *your* local time that you
uploaded the file, not the server's time (which is contrary to 1) above).
3) Otherwise, it may be that the time is merely wrong on the server machine.
If you're in the US, what is the time difference between your eastern,
central, mountain and pacific time zones? (or whatever your timezones are
called), or where-ever you live, your country might cross several time
zones....you might be in one, with the web server located in another zone,
with 6 hours being the time difference.
I need to ask......why does/should the time difference affect your ability
to publish the site? You say "almost impossible to use the publishing
feature". What is it about the time difference, that makes it almost
impossible?