Excessive general system services data

I'm having the same issue with System Services > General using an excessive amount of data. I got the message from my carrier that I was nearing my data cap for the month and dug through to realize "General" had used 12.1 GB of data!

I am connected to WiFi most of every day so I'm generally pretty thrifty with my data usage, so common perpetrators are all turned off.

Automatic App Updates - OFF

Background App Refresh - OFF

iCloud Drive Cellular Data - OFF

Wifi Assist - OFF

I looked on the carrier side of things, and the majority of the data stems from repeated 135 MB chunks of data, continuously used from 11pm to 4am while I was asleep on July 30th. Again, didn't have any updates running or anything like that.

Is there any way to dig deeper into what in "General" could be causing this? Based on what is listed beneath General (Personal Hotspot, Messaging Services, etc) my gut is it doesn't have anything to do with those, but I have no clue what else "General" consists of.

I'm on an iPhone X running iOS 11.4.1 on AT&T

Do you happen to have automatic downloads enabled? Have a look at this article: Turn on Automatic Downloads for iTunes Store, App Store, and iBooks Store purchases

On your iPhone, iPad, or iPod touch

1. Tap Settings > [your name] > iTunes & App Store.
2. Turn on the content that you want to automatically download.

After you turn on Automatic Downloads for music, apps, or books & audiobooks on all of your devices, all new purchases that you make in the iTunes Store, App Store, or iBooks Store on any device download automatically to all of your devices.

If you turn on Updates, any new versions of apps that you currently have on your device automatically download when they're available.

You can turn Automatic Downloads on or off over your cellular network on an iPhone or iPad Wi-Fi + Cellular. Go to Settings > [your name] > iTunes & App Store and turn Use Cellular Data on or off. Cellular Data downloads are limited to a file size of 150 MB or smaller.

You can also check which apps are using data from your iPhone settings. This article will guide you: Check the cellular data usage on your iPhone and iPad

View how much data you're using

To see how much cellular data that you've used, go to Settings, then tap Cellular or Mobile Data. If you're using an iPad, you might see Settings > Cellular Data instead.

To see how much cellular data an app is using, scroll down to find the app. If you don't want an app to use cellular data, you can turn it off for that app. When cellular data is off, apps use Wi-Fi for data.

To see the cellular data usage for individual System Services, go to Settings, then tap Cellular or Mobile Data. Then scroll to the bottom of the screen and tap System Services. Cellular data can't be turned on or off for individual System Services.

Depending on your carrier, you may see overall cellular data usage displayed on this screen. If you don’t have this option, or have questions about your data usage, contact your carrier.

I'm having the same issue with System Services > General using an excessive amount of data. I got the message from my carrier that I was nearing my data cap for the month and dug through to realize "General" had used 12.1 GB of data!

I am connected to WiFi most of every day so I'm generally pretty thrifty with my data usage, so common perpetrators are all turned off.

Automatic App Updates - OFF

Background App Refresh - OFF

iCloud Drive Cellular Data - OFF

Wifi Assist - OFF

Is there any way to dig deeper into what in "General" could be causing this? Based on what is listed beneath General (Personal Hotspot, Messaging Services, etc) my gut is it doesn't have anything to do with those, but I have no clue what else "General" consists of.

I'm on an iPhone X running iOS 11.4.1 on AT&T

Did you ever figure out what it was? I'm seeing the same chunks of 135MB on AT&T.