I bought my brand new monster a couple of days ago, and tried rapidly to test the http control. Unfortunately, I could never make it work: sometimes the login appeared, but if I entered the login and the code, the window always came back with empty fields. I looked deeper into the manual and opened the requested ports on my firewall, but nothing changed. Then I got a phonecall to Nikon to request for help, but the guy seemed to be as surprised as I was: everything was set correctly, but it still did not work... The good thing was that he advised me to try on a Mac...
Which I did this evening: everything working fine, could take pics from the Mac on my D4... So? What the hell??? Then I thought I should try to inactivate my firewall on the PC and test again... And it worked!!!
So the firewall was guilty. Then, got to Nikon to give them the tip, and tried again, without remembering that I had set on the firewall again to go on the internet... And it worked...
SO: if you get the same symptoms as me on a PC (I guess it's unlikely on a Mac), then open the ports (as indicated into the network manual), then switch off the firewall (being offline), try. If it works, then reactivate the firewall and try again!
Unfortunately I didn't figure yet how to make it work from the iphone...