Sometime ago w/out apparent cause it started. When I try to turn on Wi-Fi by icon or switch in settings, icon changes like it's on, but when I navigate to other place and back - it's displayed as off again. And Internet is not working via Wi-Fi. Also, I tried to change bandwidth frequency from automatic to say 5, same story - when I go somewhere and back it's on auto mode again. Is it more probably software or hardware issue? What can I do to check further?
The device is Xiaomi with Android 6, if it matters.