Slow speeds on Gigablast, down to 5mbps regularly.

First, what model modem and router do you have? Can you show the signal levels from 192.168.100.1? Does the problem affect wired and wireless devices? Cox doesn't throttle, so it has nothing to do with your cap. What speed do you get wired direct to the modem? Remember to reboot. Last, how does the coax get from the street to the room the modem is in? Cox only charges for a technician if the solution is any wiring issue inside the house(past the dmarc).