I've never been active on this forum, but as of recent, it seems a lot of people are having issues with their speeds being much lower than intended. I did a little digging through other posts and it seems with all the people being home due to this pandemic, there's a node (network) congestion. I'm not saying this is YOUR specific reason for getting lower speeds, but it certainly could be. I'm personally paying for 300 download/30 upload and I've always exceeded those speeds but as of recently, I'm barely getting over 200 download, and lots of lag for online gaming.
Don't waste your time calling for a tech unless you ABSOLUTELY think it's necessary because I can tell you personally that having someone come and check our wiring and some other ** outside the house, literally did NOTHING! My guess, it's 100% on COX to fix this. Good luck.