My guess is it's two problems. First, a peering issue between Cox and XO. Are you in AZ or West coast? I know within the last two weeks Cox has been working on the issue. It was causing alot of issues with Google services (Youtube, Google Voice, Google Play, etc). That would explain some of the packet loss and latency at Hop 12 of the provided tracert.
However, I think the main issue is the gateway itself. Notice that the highest packet loss comes at the last hop, which is the public IP of your gateway. I think you would be much better off trading in the gateway for a stand alone modem and investing in a good router. Especially if your trying to run business grade services through it. Thats like entering Nascar with a Go-cart. 
Perhaps it would help to see the traffic from the computer out. Can you run a basic Tracert to cox.net from the computer hardwired to the gateway?