For this product, Bluetooth is used for signal transmission to control the device operation. The work flow is to give commands by using the App and then transmit the commands to the device via Bluetooth. However, Bluetooth technology has its limitations, such as the failure to transmit in long distance, and the possibility to be blocked or weakened by any obstacles. And the human body itself also has a strong weakening and shielding effect on the Bluetooth signal, but please rest assured that the Bluetooth signal is not harmful to human body. In some cases, the Bluetooth signal may be interrupted in some postures or positions which will disconnect the device and make it cannot be controlled through the App. We are sorry for that problem, and we highly recommend you change your posture or position so that the problem will be improved.