Could not connect to React Native development server on Android

Solution 1:

In my case the problem was with Android security policies. According to the documentation:

Starting with Android 9.0 (API level 28), cleartext support is disabled by default.

But the application tries to access Metro Bundler through HTTP, right? And that's why it can't. In order to enable cleartext traffic, open your AndroidManifest.xml and add android:usesCleartextTraffic="true" to <application> node.

For example:

<application
    android:name="com.example.app"
    android:allowBackup="false"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:theme="@style/AppTheme"
    android:usesCleartextTraffic="true">

You can find more solutions in this SO: https://stackoverflow.com/a/50834600/1673320. OP's problem is different, but similar.

Solution 2:

From the Docs: http://facebook.github.io/react-native/docs/running-on-device.html#method-2-connect-via-wi-fi

Method 2: Connect via Wi-Fi

You can also connect to the development server over Wi-Fi. You'll
first need to install the app on your device using a USB cable, but
once that has been done you can debug wirelessly by following these
instructions. You'll need your development machine's current IP
address before proceeding.

Open a terminal and type /sbin/ifconfig to find your machine's IP address.

1. Make sure your laptop and your phone are on the same Wi-Fi network.
2. Open your React Native app on your device.
3. You'll see a red screen with an error. This is OK. The following steps will fix that.
4. Open the in-app Developer menu.
5. Go to Dev Settings → Debug server host for device.
6. Type in your machine's IP address and the port of the local dev server (e.g. 10.0.1.1:8081).
7. Go back to the Developer menu and select Reload JS.

Solution 3:

Run this and it worked for me

adb reverse tcp:8081 tcp:8081