1. Check whether the ring is charged fully 2. The distance between CIRCUL and Mobile is within 10cm for bluetooth connection 3. Check whether the Bluetooth function of the mobile phone is turned on 4. Whether the Bluetooth permission of the APP in the phone settings is turned on 5. Disassociate ring in APP firstly, and then re-add the ring again 6. Try to uninstall and reinstall the “CIRCUL+” APP, and choose to allow all app permissions during the installation process,otherwise some functions may be unavailable.