Airsense 11 shutting off ..

We have a friend who has an Airsense 11. The mask seal is a happy face but he claims that it shuts off sometimes during the
night. He has tried turning off the Smart Stop feature. But he claims it still shuts off. He wakes up then he needs to press the button
on top of the machine to start it up again.

Is the machine faulty?

not sure if this will help. I feel the same happening to mine. I unhook the air hose and reconnect. I think mine was a used one, they cleaned up and the air wheel is worn out.... but not sure.