Good luck getting any answers to this problem..
I have two android devices that exhibit the same issue. I also have an IPad that does not, just like your situation.
The android devices are a phone (LGThrill updates to 2.3.x ) and a Samsung Galaxy Tab 10.1, (was running 3.1 is now running 3.2)
In all cases no matter what version of Android I was running the problems you ask about were present in my setup as well.
On reading the posts here I have tried various things,
Router, No Router, Ports Open, Ports not open, Firewalls On and Off. In different networks and in the case of the phine I turned its WIFI Hotspot and connect my computer directly to the phones WIFI hotspot. On the phone I could easily hit a web server running on my computer, but the problems persist.
I have given up and have abandoned using AppGameKit for my projects... Good luck to you
Lonnie Allen Watson
rmag.blogspot.com (blog)