Well ... I was finally able to resolve the issue!!
In my opinion the port 80 has been blocked by the ISP; and due to lack of complete information on part of the owner, I could not get the ISP to open port 80 for mobile connections.
So, what I did was as follows:
Changed the webviewer / HTTP port to 559 (this makes me manually put 192.168.x.x:559 to open the local webviewer)
and also port forwarded the same, including the range 554-558.
And .... now iPolis mobile works just fine.
to reach to this point I had to go through intensive port checking and testing, as I was not able to open port 80 no matter what I tried.