I've been having a lot of trouble in Chandler, too. It's not specific to any time of day (though I don't really check after 8pm or so), but whether I'm playing a game or working, I'll get random internet stutters, rubberbanding in my games, long loading times for webpages I need for work, and so on. I've reset my modem several times, unplugged and replugged everything, and so on.
I recently upgraded to Gigablast, got a new modem, upgraded to Google mesh Wi-Fi routers, hardwired my computers to the routers, and the problem seems to only be getting worse. I get that Cox is probably having trouble considering how many people are now working from home and going to school from home, but it's been so freaking frustrating having the internet randomly slow down.