Turn on Bluetooth and GPS on your phone and grant the Location permission for the NoiseFit app.
Open the NoiseFit app and check to see if your watch can connect automatically.
If the watch can connect automatically, this issue may have occurred because the NoiseFit app is prevented from running in the background. If you are using an Android phone, you need to add the NoiseFit app to the protected list in the background. If you have installed third-party phone manager apps on your phone, add the NoiseFit app to the white list using the apps.
If your watch cannot connect automatically, connect them manually. To do this, open the NoiseFit app, go to Devices, and then go to Bind device.
If this issue persists, perform the following to troubleshoot:
-Disable and enable Bluetooth on your phone and try again.
-Restart your phone and reconnect the phone and the watch again.
-To reduce the chance that the NoiseFit app is cleared from the background, Lock the App in the background.
-Unpair your watch from the phone using the NoiseFit app and then pair them again.
-For Android users: Open the NoiseFit app, go to Devices and then select unbind and pair two devices again.
-For iOS users: Open the NoiseFit app, go to Devices and then select unbind and pair two devices again. On your phone, go to Settings > Bluetooth, touch the exclamation icon next to the Bluetooth name of the paired watch, and then touch Forget This Device to delete the pairing records for reconnection.