If the gas burner stops burning, there is a chance that the HI LIMIT safety switch may be tripped. To reset the HI LIMIT press the red button one time. This may reset the burner. The HI LIMIT is set to trip at around 350 degrees but other factors could cause it to trip at a lower temperature.
If the smoker is installed through the wall the control panel will be mounted above the doors. The HI LIMIT switch button will be sticking through the bottom of the control panel.
If the smoker has the control box on the side, the HI LIMIT is located inside the control box.