Few Comcast customers were unable to connect to 3D Warehouse from the SketchUp client and the behavior was attributed to “smart packet protection” setting on the Comcast router. This “protection” was an extra layer of blocking or security for Comcast customers. It was a feature that Comcast implemented on all customers, but had since disabled on all customers because there were many problems with it. So, if you are unable to 3d Warehouse and still have this setting enabled on your Comcast router please disable it and try again.