I received my rMBP last week and I had ordered the TB-->GbE adaptor. I normally would set up the machine from scratch, but I was too lazy and my MBA was perfect so I used Migration Assistant to transfer apps, documents and settings from the MBA to the rMBP. Everything was working fine until I tried the GbE adaptor. When I first plugged it in, the rMBP took me directly to the network settings page and said it needed to initialise the new network interface. Great. Or so I thought. It correctly listed Thunderbolt Ethernet in the list of interfaces, but it stubbornly refused to accept that a cable was connected. I tried various cables and different ports on my router and nothing helped. I even tried to use the other Thunderbolt port, to no avail. I started thinking that maybe the adaptor is broken so I tried to use my old USB Ethernet adaptor on the rMBP and what do you know? It wasn't working either. Great. I then tried both the USB and Thunderbolt adaptors on the MBA and they were working perfectly fine. I swore a bit at this stage. Luckily, I found that you simply have to remove the USB and Thunderbolt interfaces from network settings and add them again on the rMBP. I suspect that something had gone wrong with Migration Assistant in the settings transferral. After I did that both adaptors started to work on the rMBP.... Except that my so called Thunderbolt Gigabit adaptor was only transferring at 11 MB/s to my Synology NAS, which is just over 100 megabit speed. $%£$!!! &*^ $£^$%!!! I then realised that it was actually still transferring over wifi , despite the Ethernet connection being on and after I disabled wifi, I got around 96 MB/s. Result.