Xfinity recently announced they have updated their data usage meters, and have increased the amount of data allowed each month (from 1 TB to 1.2 TB) before charging for an overage. Upon viewing my data usage for the last several months, I see I used about 200 GB in March, the same in April, over 1330 GB in May, over 2300 GB (2.3 TB!) in June, and nearly 900 GB through half of July. My internet activity has remained about the same throughout this time. I know I can sign up for unlimited data, but I'm looking for a satisfactory explanation for that ridiculous increase in data usage.
Look at your online account and see if “Wi-Fi access” is enabled or disabled. This is where Xfinity tells you that if you enable it, then guests in your house can access your Wi-Fi without a password. However, this turns your Wi-Fi into a public hotspot if it is enabled. Therefore anyone within distance of your Wi-Fi can access your Wi-Fi, so you may have neighbors and strangers using your data without you knowing it. Check it out in your account and be sure it is disabled if you do not want to be a public hotspot.
I was not aware that not disabling "xfinitywifi" in my account would allow guests, or anyone within range of my gateway, to gain access to my wifi without knowing my password. In fact, I was not aware that this option even existed. Not good if you live in a condo or apartment, where close neighbors can access and use your data without permission. Thanks for the very helpful info.