Have you tried to run it on Android Studio itself after this command:

npx react-native start --reset-cache

Restart your phone.

That’s all I had to do and the issue fixed itself.

I am creating a simple app. It was working smoothly in emulator but after running on real physical android device it is not working on both emulator and device.

I am using react-native-cli.

After running

npm start android

I am getting below screen.

And in device it showing loading please check the below image. I patiently waited but still no luck its on the same loading screen.