I've noticed this 'double-usage' problem as well and began monitoring my own traffic by installing DD-WRT on my belkin play router. But more so I've just plain noticed the amounts are never close.
Before I continue I'd like to point out i have a degree in Electronic Engineering, years of experience in Networking and I make a living as a programmer. So my level of knowledge is advanced.
I contacted Cox support Tier 2 a week ago and was told they would look into it and they would get back to me and I am still waiting on a response. The fact of the matter is that my internet usage really hasn't changed over the last couple months while I've noticed a significant increase in what Cox is reporting.
You can see my router traffic on my WAN here: http://prntscr.com/1ksuza
You can see what Cox is recording here: http://prntscr.com/1ksvc8
Now if you compare the dates, you will notice that cox is reporting almost double of what my router (DIRECTLY connected to my cable modem) reports on most days. But the important fact is the amounts are NEVER even ever close
- On the 11th DD-WRT reports 11.4 Gb but Cox reports 19.21 Gb (~ Double)
- On the 10th DD-WRT reports 15.9 Gb but Cox reports 8.02 Gb (~ Half)
- On the 9th DD-WRT reports 4Gb but Cox reported 7.21 Gb (~ Double)
- On the 8th DD-WRT reports 8.7 Gb but Cox reported 16.43 Gb (~ Double)
- On the 7th DD-WRT reports 6.2 Gb but Cox reported 11.1 Gb (~ Double)
- On the 6th DD-WRT reports 16.6 Gb but Cox reports 32.89 Gb (~ Double)
I know these systems are not fool-proof but I also monitor my traffic heavily and quite guardedly. I have encryption on my WAN and MAC-Filtering. I monitor my connections like a hawk. If I had any malware/virus on my computer that was attributed to this usage my WAN would show it. So this isn't a case of people jacking into my network or malicious software sending data into the ether. It's a case of Cox's numbers not adding up to my numbers.
The fact that the variations between what my router sees and what Cox sees are by ratios of 2:1 or 1:2 makes it clear that this isn't a case of a few mis-reported Gigabytes .
Frankly, I would like to know whats going on and stop being told by support that I've been 'warned' and that I have 'abuse notices' on my account. I've been a faithful customers for almost 10 years now and I think I deserve some answers, not the run-around.