We have just had our cameras and DVR box changed so the cameras record in colour day and night. We have noticed that there is a humming noise on the live view and on playback. The guy that fitted it has said there is a sound button the bottom of the app which I assume he means the noise reduction button you can either have this set to 1 (closed) or 5. Changing this makes no difference whatsoever so I am thinking it’s something that needs changing on the settings on the DVR. Do you I know what I need to change as this is highly annoying. My husband and myself both have iPhones and it does it both