Check if you fall into any of the following situations that might cause the blurriness or disfunction of your camera's night vision:
1. Your camera is facing towards a large whitewall or other kinds of reflective objects. Please try facing your camera away from the object.
The white color or contrast color of those might interfere with the camera's night vision, therefore result in the blurriness or disfunction of the night vision
2. There is a dim light in the dark space in which your camera is operating. Please turn the dim light source off and see if your night vision is back.
Having a dim light might prevent the night view from being turned on.
3. There are objects that are too close to the camera lense. Please remove those objects from the camera.
Please confirm that you have prevented the above circumstances, then reboot your camera again to restart the built-in infrared lights.