I wonder whether Safari in IOS 11 has a bug. I used over 4GB of data in under a month. Without doing anything like watching videos. Since I first bought an iPad, the most I had used in a month was 4GB, when I was on unlimited, so finally changed plans to the 5GB over 150 days on T-Mobile. So on the 20th I renewed for another 5GB. Got warning about 4.5GB of data since then. At least the rate is low, but I expected 5GB to last 2-3 months. iPad Mini 4. I have cellular data off for app store, since that was a big data hog on unlimited.