This is a personal opinion only, but I think the upstream power levels specified by Arris might not be applicable. The upstream power determines how "loud" your modem has to talk in order to send data on the internet. (Really this means sending data to the Cox node but I'm oversimplifying). If the Cox node isn't receiving your modem clearly, it can ask the modem to "talk louder" which means increasing the upstream power. If your upstream power is lower than expected, that could mean that node can receive your modem without needing a lot of power and that can mean you have a very good connection. So my personal feeling is that a lower upstream power can be fine. But if the upstream power is too high it indicates a problem. Maybe someone with more technical knowledge can offer a better explanation.