zuk z1 immediate restart problem in standby mode

when use wifi hotspot and after using it with my laptop, and when i turn off hotspot and switch off the screen of mobile, after few minutes later phone vibrates and automatically restarts one time in standby mode. this happens in standby mode.

i am using adguard as local vpn in logcat last entry shows for
handle_blank_event:dpy:0
panel_power_state_0