Okay, it appears you are trying to do two different things. So, to break it down:
(1) If you are trying to upgrade the iPad to iOS 6.1.3, then get the software from this link:
http://www.ipadforums.net/ipad-hacking/24939-official-apple-ios-firmware-download-links-ipad.html
This way, you don't have to worry that iTunes can't get to the server as you'll have the firmware you need. You can do the shift/restore process to restore the iPad to iOS 6.1.3, which is the newest (and only) iOS you can upgrade to.
Do note, however, that iOS 6.1.3 is not jail breakable at this time. If you upgrade, you will lose your jail break.
Or,
(2) If you are trying to re-restore iOS 5.1.1 onto that iPad - do you have SHSH blobs for that iOS? Because the re-restore will not work if you don't have the blobs.
Marilyn
P.S. I moved your other post you started today on this same topic (over in another thread) to this thread. Making more than one post not only fragments the conversation and makes it hard to follow - it's against the forum rules. Please keep any follow-ups, discussion or updates on this topic to this thread; do not start another. Thanks for your understanding.
