Check out: https://arris.secure.force.com/consumers/articles/General_FAQs/SB6183-Cable-Signal-Levels. If you have an Arris modem you should be able to see the results for each upstream and downstream channel. The tech should be able to tell you what they are also, and if they are too high or too low. If they are right on the high or low specs then you could be having issues. Also temperature can affect the overhad cable, so those values may change.