dev server returned error code 403 react native

A) Set the new port for dev server
User command react-native start --port=8088
or
yourproject\node_modules\react-native\local-cli\server\server.js to set the the available port say 8080
now use react-native start to start server on 8080

B) Now to establish communication between emulator and dev server, use below command
adb -s emulator -5554 reverse tcp:8088 tcp:8088
i) 5554 =>emulator port (adb devices command will tell you emulator port but if this command is not working then set the path C:/../android-sdk/platform-tools in Path environemnt variable )
ii) 8088 =>server port

C) run the command react-native run-android

D) Follow below steps updating Dev server path in emulator

i) Ctrl + M for windows to open your dev menu for the emulator.
ii) Click Dev Settings
III) Under Debugging select Debug server host & port for device
IV) Enter the url and port for your application as 10.0.2.2:8088

1. Press cmd + M (Ctrl + M for windows) to open your dev menu for the emulator (Please make sure your react-native app is open in the active window of the android emulator before using this command)
2. Click Dev Settings
3. Under Debugging select Debug server host & port for device
4. Enter the correct url and port for your application in your case 10.0.2.2:8088

Once you do that you can reload your application and it should work.