I've had Verizon's Samsung Note 5 for about 1.5 years. I don't have (and don't really want to pay for) an unlimited data plan so I use cellular data sparingly and use my home WiFi when downloading apps, updates, etc.
This morning I discovered my phone had, on its own, downloaded the Android 7 system update using my Verizon cellular data. Previously, the phone would only check for system updates and then notify me that an update was available for download (at which point I would use my WiFi to download the update)
How can one prevent Android from using the cellular network to download system (Android) updates without permission?
(I tagged this as Marshmallow since that was the version that had the auto-download bug in it, but I want to know how to prevent auto downloading of system updates in Android 7.0 also)