Thanks for using our answers forum! I do apologize for any inconvenience you're experiencing while trying to set up your Slingbox. That is odd that you are able to view on your SlingPlayer for iPad but unable to complete Setup on Slingbox.com when you are on the home network.
Here is an article from our support site with some steps that you can take to resolve the issue:
Hope this helps, please reply back if necessary!
The Sling Moderation Team