SB1683 Only 100mbs Link Speed Network Connection

When I connect my computer directly to the modem using a cat 5e or cat6 cable it only connects at 100mbs. I am talking about the "link speed" (transmit/recieve) , not the upload/download speed. When I connect my computer directly to the router the link speed is 1000mbs so I know it's not the computer.  I recently checked my download speed and it was only 95mbs and I am paying for 150mbs so I decided to try and figure it out and this is what I discovered. When I logon to the  modem I don't have any options to reset it either. I think it might have been removed in a firmware update.  Cox says I am getting the full 150mbs to the modem. Any ideas?