Hello everyone today i have came up with an very easy solution to a serious problem. Since android version 4.1.2 jelly bean has been released usb tethering had been made easy that is connecting phone directly to the pc and access internet and blocking the unnecessary devices which are accessing the internet while connected through usb tethering.
The problem can be permanently fixed through following steps and the good news is that there is no requirement that the device should be rooted and the method works on the all the stock roms as well as modded roms.
» Enable developer mode in the setting ( Go to setting » about phone» find build number and click on it until the developer mode is enabled.
» Enable usb debugging under Developer options you just enabled
» Connect the device with the usb to the computer but make sure you have already installed Android SDK tool platform installed in the computer.
»Start an adb shell : adb shell
» Now in adb shell run this command
settings put global tether_dun_required 0
Note :- following process is tested in Nexus 5 and Nexus 6 running on latest android marshmallow 6.0 by Xda developer guys.