Terrible Internet Connection!!!!!!

I have been back and forth with Netgear and Cox trying to solve my gigablast approved devices CM1000 modem and R7000P Router only reaching below 168mgbs sometimes reaching way below 100mgbs. Netgear said it was the power that was wrong and should have been positive 7 not in the negatives as mine currently is still.  Modem: https://imgur.com/CR4iGwl  SpeedTest: https://imgur.com/INa4zzo I'm tired of going back and forth for a year now. I don't want to get cox's devices for rent, that is why I bought my own as their website said should be approved!!! I will see what happens this round, or can someone actually help on this forum??