Surprise to see no replies. Anyways, got it resolved by opening up the port 4747. With qlikview 10 it was working with port 80, but when upgraded to 11, I needed to open port 4747 which was strange. As noted in some of the blogs, first the request comes to 4747 when it fails then the request is transferred to 80. This was my assumption.
Not sure why you didn't get any answers and I didn't see your post till now. This is strange being Tunneling is a default setting when you use QVWS. You only have to set it up if you are using IIS. I do find this interesting " I am able to open the document in local intranet zone but not from some other location" and you have blocked out the two things I need to see in your screen shot. But check the linkmachine name.
This is after I gave the linkmachinename which is say 'my.qvw.com'. The blocked thing is same my.qvw.com. So the error starts with qvp://my.qvw.com, which is succeeded by iis_authenticate part, the tunnel part is ...tunneler=http://my.qvw.com.
I am not sure why the error url and the browser url are different.
The port 4747 on the server is open but is blocked in the firewall, so internal users i.e intranet users were able to open the document, but external users failed as there request were not allowed to enter.
It is strange to notice that with qlikview 10 external users were able to enter just with port 80, but with qlikview 11 it is asking for 4747 as well.