Do you know what version of slingplayer your using on your IPhone? I'm using version 2.1 and I'm unable to connect on 3G but it works fine on wifi. It stopped connecting via 3G when I upgraded to 2.1 but now even when I downgraded back down to the previous 1.3 it still won't connect anymore on 3G. I'm scratching my head here.
Same thing happened to me when I upgraded a few weeks ago. Just delete it from your phone. Remove it from your itunes library, redownload and install.
Should be fine after.
Are you trying to connect to your slingbox and it says you cannot connect?
Try on a PC also, if you cannot connect with the PC also, most of the time for me, that means you need to do some sort of software update by going to the Slingbox website. Just clicking update in the slingbox viewer does not do it. YOU HAVE TO GO TO THE DAMN WEBSITE!!!
It took me forever to figure out this. One thing to check for is one of the red buttons on the front of the slingbox blinking? If so, thats another tell tale sign you need to do a software update.
They did two software updates on me in one week recently. I was like man, I just fixed this a day or so ago and now its f'ed up again. Software upgrade FTW.