This sounds like the Internet Viewing through your home router was not configured correctly.
I recommend to be on your home network and port forward your router with the IP address of your Slingbox with port number 5201 for TCP streaming. Also, make sure the uPnP (Universal Plug and Plug) is enabled in the router.
If you do not know how to do so, contact your Internet Provider and give them your IP address of the Slingbox and port number 5201 and ask them to port forward for TCP streaming.
Hope this helps!!!
Sling Media Moderation Team