Upgraded to Gigablast, only getting 200 Mbps downstream...

I recently upgraded my service to Gigablast, from the Premier 200 plan. I have the Arris CM8200A modem provided by Cox. My LAN is gigabit. My computer is hooked up via Cat6 (not wifi). Everything internal seems to look ok.

But I'm only getting ~200 Mbps down (35 Mbps up, though - which tells me that I do have the Gigablast package). Cox is supposed to be coming out this weekend, but I'm wondering if anyone else has experienced this?

I'm getting various "dynamic range window" violations in the status of my modem, when I reset things. I'm not sure if that has anything to do with anything? Could it be possible that due to the DRW issues, that my modem isn't being reset properly? Would a "factory reset" help matters at all?

I'm just trying to think of things to do before Cox comes around. I have yet to try a "direct Cat6 line" to the cable modem from a computer, but that's in the works to give it a shot (to rule out the router and switches - which is a TL-WDR3600). I'm not sure what else I can try?