Can't get past 30Mbps with Premier Internet & new modem (DOCSIS 3)

Got a new DOCSIS 3 modem today (Cisco DPQ3212), which was supposed to help me fully utilize the 50Mbps available with my cox premier internet. Speed tests continually report exactly 30mbps.

I've engaged 2 different support resources through chat.

The first "sent signals" to my modem, and asked me to restart everything. - No change
The second, asked to send a line technician out to my house.

The modem is receiving excellent signal. (Power: 2.5dBmv, SNR: 39dB). I have good quality cable and connectors, and have the modem plugged directly into the line coming into the house. There is no reason to believe there is any issue with the physical connectivity. I consistently cap at *exactly* 30mbps, and the issue is not intermittent.

I can't seem to get ahold of anyone who is willing to take a closer look, or escalate the issue to someone who can. My issue is very symptomatic of a traffic shaping policy. It's very likely some configuration needs to be updated, but I can't find anyone who is willing (or capable) to investigate the further.