I've had some very strange behaviour when using the Thunderbolt Ethernet adapter on my MacBook Pro Retina. When I plug in the cable that goes to the back of a Thompson Speedtouch ADSL router, I get assigned an IP address, DNS, default gateway. All is fine, I can browse the local network and can get to the router configuration page. However when I want to get to the Internet I can't get passed the router. However again, when I plug in my usb 3 to Ethernet adapter, use the same cable, all is absolutely fine. Has anyone got any idea what is going on with the thunderbolt - Ethernet connection?