What happened to Cox's reported data usage
I started to receive overage notification toward the end of Dec. I checked the data usage in my Cox account and found the data consumption is about 40GB+ almost everyday in Dec. As a comparison my Nov usage didn't show this pattern and I could see a more reasonable low usage (about 3GB) during weekdays and high usage (30GB) during weekend.
I looked into my router and the reported usage from my router is only about 640GB the same period. Cox's reported usage doubled what my router tracked.
What's more problematic is that my family went out of town from Dec 12 to Dec 18 and on those days the Cox reported about the same 40GB usage everyday, while my router reported less than 3GB usage per day in this period.
My router connects directly to the modem and there is nothing in between.
Cox tech supports asked me to check if there is unauthorized usage of my wifi. I checked the router's usage report and found no evidence of unauthorized usage. The highest usage was from a device that was used to stream video from Amazon, which consumed about 440GB, less than the router reported 640GB.
So what's wrong here with Cox?