Check if the tower and subwoofer’s LEDs are in solid white color. A blinking LED means a disconnection. In this case, hold RESET on the back of the tower or subwoofer for 5 seconds to enter pairing mode. On the touchscreen, tap “Speaker Setup” > “Pairing” > “Tower Setup” or “Subwoofer pairing”, then follow the onscreen instructions to pair with the digital hub again.