I've checked the surrounding area and not showing any issues that would be affecting the internet. The modem showing about a 2% packet loss from this end. Try reseating both ends of the coax cable making sure their hand tight. You can also try bypassing the router and hardwire directly to the modem for testing purposes.
The goto blanket responses offered by the moderators here actually have some merit. You'd be surprised how the amount of times I've seen experienced techs get their butt kicked by Layer 1 (myself included). I troubleshot a similar latency issue for a few days, swapping/bypassing infrastructure only to find a bad 90° F connector that I had kept dismissing because "passive devices don't go bad".
Goofy Layer 1 issues is why most techs immediately swap all the F connectors on every cable between the DMarc and the modem.
Also, most people with network experience don't necessarily have knowledge of headend/coax infrastructure and residential coax can be a nightmare due to the homeowner DIYer going to WalMart and buying the wrong coax cable for their house.
The best course of action is for "rustem" to run a brand new piece of RG6 from his DMarc (if possible) straight to his modem and hook directly to it with his PC/console, whatever and see what happens. Completely bypass the entire house infrastructure and network. If he still has issues connected directly to the DMarc, then he has enough ammo to attack Cox until they fix it.
Source: I'm an IT guy that also used to maintain/service TV headend/distribution.