it looks like changing the settings in my router did the trick.
it didn't work at first, but i noticed that when i opened the sync on the iphone, the multicast_test went crazy with data.
after that, it took killing the iphone app and restarting it for the sync to work. not sure why. in my testing, if the iphone app has been open for a while, killing it is sometimes required to make it work, but that is something i can work with.
thanks a ton for helping me get this working!
d.