Could be a hardware problem. Maybe the network adapter is faulty?

However, just to test, I went into the network setting of my box and it also initially said No about the internet connection and after a couple of seconds it said Yes. I have never experienced any consistent issue with buffering that I couldn't trace to either the provider or my network, so I would imagine there is just a delay in the network connection settings displaying the status, not necessarily a lack of connection.

Have you tried a different service provider with similar results?