[Connectivity] TPLink TC-7620 only connects at 100 but it has a gigabit port

I've also posted this on the Comcast forum as well as contacted Comcast and TPLink but have made no progress. ---- I have a TPLink TC-7620 This has a Gigabit ethernet port but I only connect at 100. I've tried connecting through a router and directly with a laptop. Each only connects at 100 It has the following config d11_m_tc7620_speedtierextreme2_c01.cm The admin page doesn't give the option to set a static speed so I can't force it. My laptop detects 1000 if I connect to anything other than my cable modem. I've reset the modem a couple of times. I've also tried introducing a switch between the modem and the router as suggested in a similar thread. I've tried several ethernet cables. any ideas? thanks