Android Tethering Turns off straight away
If your Nexus 6P is rooted:


Install Build Prop Editor app from the Play Store and launch it.
Change net.tethering.noprovisioning=true
Install Terminal Emulator app from the Play Store and launch it.
In Terminal Emulator, enter the following code sequentially:

su
settings put global tether_dun_required 0
exit
reboot