Since you are having some issues with the remote connection to your Slingbox, I recommend you to check this thread and follow the recommended steps.
I get the same message from both work and home (I'm traveling abroad right now and work and home are on different ISPs and both outside the US). The weird thing is that I can connect using SlingPlayer Mobile for Android from behind the same access points at both places so it's definitely not my connection at either place or a router/firewall issue. I also disabled my PC's firewall to ensure that wasn't causing a problem and even disabled IP6 on the wireless network adapter.
I'm on Windows 7 Ultimate x64 - fully service packed with auto-updates. I'm using a Killer MIMO wifi card but it also happens if I connect to the LAN from both places.
And, I cannot connect using either the web/Firefox plugin or the stand-alone SlingPlayer app for Windows.
So to be clear, no luck at all from PC regardless of ISP, location, firewall, or router. But luck from the same places from my Galaxy Tab using the Android version of SlingPlayer mobile.
So exactly what does W213 mean? The description of it is vague on the support site.
I've also located error code
[Advanced users: the error code is 0x92340011.]
Which states something about connection timeout. Is there a way to increase the timeout in the registry? Seems odd that this isn't a problem on SlingPlayer Mobile on Android but is a problem on the Windows client and the Firefox plugin.