To troubleshoot your network, you have to distinguish 2 separate networks. You have the Cox public network and your private network. Although you have a combo device (modem/router), the separation point is the modem.
The modem connects your network to the Internet via Cox. The router connects together your devices as well as connects your devices to the modem.
To do a speed test, you must get as close to the modem as possible. Meaning, directly connect your computer to an Ethernet port on the modem with an Ethernet cable.
You'll need a computer with an Ethernet port (Gigabit Ethernet) and an Ethernet cable (one should have came with the Panoramic). After you're connected, turn off your WiFi so nothing will interfere (consume bandwidth) during your test.
If you're getting acceptable speeds (~800 Mbps down; ~30 Mbps up), the Cox network is good. You'd then troubleshoot your network (WiFI).