If the issues started after they did service in your area, it could be an issue with their network. Not your equipment. Google PING TEST and TRACERT to learn how to run a couple simple tests that will determine if the issue is outside your home. Save the screenshots for proof.
Most technicians will avoid this since Cox doesn't want documented proof of their infrastructure issues. Don't let Cox blame you for their service issues. It took a complaint with FTC and FCC after 6 technicians came to my home in 6 months to show that the issue was with a the south west region [ langbprj02-ae1.0.rd.la.cox.net .]
Run tests through out the day, and If your result show packet loss and drops on THEIR end, you can submit a complaint form to help get the changes made.