Unfortunately I don't another machine with an ethernet port, and the Panoramic gateway doesn't have a USB port. I'm very confident it is not my machine. It's a high powered developer's Lenovo Thinkpad from work, with a gigabit ethernet port. It works on a gigabit LAN at work, no issues.
The raw throughput as tested by the technician over coax was well over 1Gbps. Logically, that would mean the Panoramic wifi gateway is the weak link here. I have seen some poor reviews online for the modem(Technicolor CGM4141), and another member wrote his speeds went up when he purchased his own modem.
So the question is, can Cox test whether the modem is actually putting out 1Gbps via ethernet without depending on my PC? The WiFi speeds are nothing to write home about either (even on a 5GHz connection sitting right next to the modem) but that's a separate conversation. Let's focus on sorting out the ethernet speed first.