Do you regularly play music on speakers of your Lenco LS-300 via an external source such as a smartphone? Then it is important to set the volume of your phone to maximum. The higher you set the volume on your phone, the stronger the Bluetooth signal to the speakers of the LS-300 is. If the volume is too low, the number of signals to the speakers and their strength is limited. Because of this there is a chance that the speakers will go into standby mode after 20 minutes because the Bluetooth receiver is under the assumption that no more signals are being received.