DIAGNOSIS The label maker's Bluetooth module is not in pairing mode. It goes to sleep after 5 minutes of inactivity to save battery.
FIX On the E10, press and hold the Power button for 8 seconds until the blue LED flashes rapidly. This forces pairing mode. Now open the SUPVAN app and tap "Connect Device." It should appear immediately. Complete pairing within 60 seconds.
IF THAT DIDN'T WORK Interference from other 2.4GHz devices (Wi-Fi, microwaves, other Bluetooth). Move the label maker and phone to a different room, away from routers. Turn off other Bluetooth devices nearby.
HEADS UP Do not pair the E10 through your phone's system Bluetooth menu. Always initiate pairing from within the SUPVAN app. The system pairing creates a generic serial connection that won't work for printing.