A lot of people have issues with packet loss. It's one of the most common issues on cable internet. But it's not one systemwide issue that the provider can just push a button and fix. It's more like hundreds or thousands of different issues that all need to be fixed separately. Unless you live on the same block as other people reporting packet loss, it's almost definitely caused by two different problems.
There are three common causes for packet loss: congestion, ingress, and defective plant equipment.
Congestion is caused simply by too much traffic on the cable network. This happens most frequently in areas where a lot of people use a lot of modern services like streaming. If all the kids in your neighborhood are streaming on Twitch you're going to experience congestion. Same goes if everyone is downloading the latest Call of Duty update at the same time. If Cox provisioned enough bandwidth so that everyone could go all out on their connection all the time, internet fees would probably be measured in thousands of dollars per month so it's not as simple as just adding more capacity.
Ingress is caused by some "leakage" in the cable network including in other homes in your neighborhood. Think of the cable network like a tightly sealed system. If there's a crack in a cable anywhere in the system, it allows noise into the system and this causes packet loss. If you've replaced all of your indoor cables, all you can do is have a tech check for noise on the rest of the line. My neighborhood is mostly elderly so I never have problems with congestion but I have problems with ingress all the time because Norbert and Myrtle are always pulling ancient cables out of the closet and using those to hook up their yard sale TV from 1982. Their action in their home affects the quality of my connection. That's the disadvantage of a shared system like cable internet.
Defective plant equipment means a problem any part of the cable network (node, amplifier, splitter, tap, etc.) that is outside of your property. Only a Cox tech can identify and correct this type of issue. It can happen anywhere at any time, and can affect anything from a single home to an entire neighborhood.
Learning how to read the signals and logs from your modem can help you to narrow down the issue, but only a qualified Cox technician can properly identify and resolve most of these issues. Unfortunately some technicians are more qualified than others.