I'm not sure how many devices you have using the router wifi and lan but I use an app called Data Usage in the windows App store which is free. There are plenty others out there to choose from as well. It has an export feature to save data with charts as well. I have traffic meter turned on in my router (Netgear R8000) since the data cap ** was initiated (dropped from 2tb to 1tb on my Ultimate package which is why I got that package in the first place not just the speed and now getting rid of cloud storage too and pushing us to drop box which I prefer Onedrive instead as a replacement, but I digress...)
Keep in mind that I have calculated less than 100meg difference between the App and my router so this is actual data usage between devices. Remember to keep copies of this data as evidence should you go over your data. There have been many reports of inaccuracy's of data usage by Cox customers by as much as a 500g difference already. I have never had to monitor my data usage before until now so may as well get started to make sure Big Corp monopoly does not try to stick it to us again and again even more.
Option1: Synology has a router that lets you bridge you Cell phone to act as an additional Wan and failover. Some people have dropped Cox all together and used this router with their Cell phones unlimited data plans that have good signal of course. Just another option.
Option 2: If you can afford a second account with another cox modem then get a bridge multi-wan router that will combine both modems to act as one doubling your up and down speeds and giving you 2Tb of data.
I have also done this in order to monitor my contour flex streaming service which is suppose to not count towards my data usage and since Cox is pushing DropBox I believe that Data Usage should not count either but that's a different issue. So in theory I should show more usage on my end vs Cox usage report we will see after the first month since I got Flex 2 days ago.
Also note that If you have a Cox modem that has built in wifi and your not using it be sure to disable it because it will use data even if you not using it depending on model.
I will be moving on to ATT Fiber Next year when its suppose to be available in my area to get away from this disloyal Company called Cox... I have even tried to get gigablast from them but won't be here for another 5 years or more or never so they got the monopoly on us here but not for long. Been with them since 2005 and apparently loyal customers don't mean ** to them while giving 20% to 40% discounts to new customers they keep screwing with their current customers. (Apparently Loyalty only works one way with Cox) Already 3 friends of mine and 2 relatives have moved to ATT Uverse with the 1G plan unlimited data NO CAP and is now offering no data caps to people who already have other services from ATT like Cell Phones, DirectV, etc. They are sure capitalizing on Cox data cap screw up for sure.
