If the earbuds exhibit abnormal behavior, e.g. sound cutting in & out, very short range, static noise, touch control not responding, etc., please do the following.
1) Delete or ‘forget’ the Avantree TWS109 from your phone’s Bluetooth menu.
2) From its OFF state, press & hold on RIGHT earbud for 5s until the LED flashes RED & BLUE alternately. Double click and the LED will light on RED & BLUE simultaneously (looks pink) for about 2s.
3) After a successful reset it will automatically enter pairing mode. Please see section 2 to pair & connect your phone again.