The problem must be within your specific setup as it works just fine for others including myself on both wifi and 3G at home or remotely in either conenction senario.
When you say it works fine when using wifi, was that only at your home location, or did you test it on a remote location? Have your ran the remote setup wizard and opened the default port 5001 on your router for remote viewing?
If I have my iPhone in wifi mode it links to my home network through my router. I can view slinging programing just fine. If I go to an outside location and activate the sling viewer normally ( without wifi connection to my home network) I cannot connect.
Sling media states in their help forum that I need to upgrade my sling solo. I don't understand how it can work at home but not on the road.
Again, can you view your slingbox solo with your iPod Touch even though wifi from a location outside your home network?
If not, then it's your router setup. If you havent port forwarded port 5001 to the internal ip addfress assigned to your slingbox, you will not be able to connect remotely (outside your home network with wifi; much less 3G.
The iPhone/iPod app works just fine with the solo.
1. Make sure your runing the latest firmware released for the solo.
2. Make sure you have the latest iTunes installed on your computer and are runing the latest apple firmware (or jailbreak alternative) released for your iPod Touch.
Rerun the setup on the solo (either via the web portal or by using the stand alone slingplayer desktop software on a computer from within your home network. More specifically, make sure you setup the internet viewing option that will configure your router for port forwarding in the manner I described above.