Hello Kevin

                    We understand that you are having slow speed issue, speed plan you are opted in by your internet service provider is a compatible speed plan but still you are facing slow speed issue is because of the cable signal level issue. There are some important things that should be within a specific range in order for the internet to work properly. First, the SNR should be above 33 on all of them. The downstream power should always be between -15 and +15. The closer to 0 the better connection. Finally, your upstream power should always be between +45 and +51. On all of those values you should not have more than 3 decibels (or dB) between the lowest and the highest, By having the values in less than that, your device will have interrupted connection, slow or no connection at all.

                   Cable signal level will be different for every modem so may be the internet service provider sending signal level which is needed for their modems which is not matching with our Arris device so we would suggest you to try changing the cable signal level by contacting your internet service provider then monitor connection. 

I understand that the upstream power readings are slightly out of spec, but fail to see how that would prevent the modem from providing gig service. I’m getting a solid 560mbps from the modem, just as I was prior to the request to upgrade. If the upstream power was the issue, then wouldn’t I have been having problems with the 500mbps service? If upstream power was the issue, wouldn’t the modem at least been attempting to provide some varying speed between zero and a gig?  As it stands now, I have Cox blaming the modem, and Arris blaming Cox. I’m fairly confident here that Cox is the issue, but I need something more for ammunition than complaining to them about 10 dbmv of upstream power.