This is what I've gathered from your first reply and base my response on. You have Verizon FiOS and even when at home, you're having issues with your Slingbox.
First thing we should rule out is if there's a problem with your wifi connection to the router. This is pretty easy to determine if your WiFi is the issue by running a speed-test, or, connecting your computer to a wired network.
Other than that, I'd check to make sure there's not a major issue with the network cable connecting your Slingbox to the network.