http://www.digitaljournal.com/tech-and-science/technology/android-oreo-warning-as-bug-eats-up-mobile-data-allowances/article/501769

Android Oreo warning as bug eats up mobile data allowances

Posted Sep 6, 2017 by James Walker
Google is rushing to fix a bug in Android Oreo that's draining mobile data. The issue is understood to be left over from the preview builds of Oreo. It causes the phone to always prefer mobile data, even if a Wi-Fi network is available and connected.
Android Oreo
Android Oreo
Google
Android Oreo was launched a couple of weeks ago and is currently only available to owners of select Google devices. This means the number of affected users will be very low compared to the wider population of Android smartphone owners. It's still highly frustrating for those who have received the Oreo update though.
ZDNet reports users first said they'd experienced the problem on Reddit. After noticing spiking mobile data usage when the Oreo update completed, many observed their phone continue to complete downloads over its cellular connection instead of Wi-Fi. Users described the surge in usage as "huge" and worried it could cause people to blow through their data cap.
As more people chimed in, Google support staff confirmed the existence of the problem. The company's currently working on a fix to resolve the situation. There's no word yet on when it will be available.
Although it's being treated as a "bug" by users, the annoying behaviour seems to stem from one of Android's developer features. Google apparently left the "Mobile Data Always Active" setting enabled when it released Android Oreo publicly. This option is usually hidden under the Developer Options menu and should be turned off for most users.
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When it's active, the setting allows Android to keep communicating over mobile data, even if a Wi-Fi network is available. The cellular connection remains active all the time and becomes the preferred radio for all Internet access. Besides draining data allowances, it could also reduce the battery life of the phone.
This is the second major issue to be found in Android Oreo since its release. Google is still investigating scores of complaints about Bluetooth problems affecting pairing with certain devices. Pixel and Nexus phones are said to be having connection dropouts while initiating pairing with Android Auto and some speakers. Google has acknowledged the reports but is yet to detail the cause of the issues.
For users suffering from the mobile data bug, there is a simple way to force Android back to using Wi-Fi. Open the Settings app and scroll down to the bottom of the page. Tap "About phone" and then press the "Build number" section seven times to enable Developer Mode. Head back to the main Settings menu and open the "System" category. Tap "Developer options" and then find and disable the "Mobile Data Always Active" checkbox. According to user reports, this should restore the more intuitive mobile data behaviour from Android N.