Question

Fixing tethering on Android KitKat - Android Tutorial

Answer 1

Google made a change in Android 4.4 which allows operators to know when users are using tethering and conveniently block tethered devices from accessing internet.

This can be fixed permanently using the following procedure:

Enable developer mode (Go to Settings -> About phone, and click on the build number until the developer mode is enabled).
Enable USB debugging under Settings -> Developer options
Connect the device with a USB cable to a computer with the Android SDK platform tools installed
Start an adb shell: adb shell
In the adb shell, run this command: settings put global tether_dun_required 0