I had your exact experience with not one, but three different expanders. Linksys support took me through a wide range of steps - I could always connect to my network, but, as in your case, I could never connect to the internet. As with you, once I disconnected the expander, I could immediately restore a connection to the internet. Per Lynksys support, I returned two expanders for new units, finally returned a third for a refund. I returned two of my units to Fryes, a large retailer in California that aggressively puts returned product back on the shelf, labeled and shrink-wrapped in most cases. I noticed that of about 32 Expanders on Fryes' shelf, almost half of them were returned units. The store had no explanation. While one conclusion from all of this is that the product is flawed, I suspect that there is a step or sequence of actions in bring up and connect to the expander that is not clear or intuitive (or in the installation directions) that is being missed. If this is true and anyone has discovered what is being missed, an explanation will most likely sell a lot of expanders.