The device has 4G, but NetworkInfo.isConnected() show that there is no Internet connection

Question

I have one strange reported by one of the clients. They are on 4G, but in the app it says that they do not have Internet connection.

In the app I am using this logic to inform the user that they have connection or not.

public class NetworkManager {

  private final Context context;
  private final SharedPreferences sharedPreferences;

  @Inject public NetworkManager(@Named(DIConstants.APP) Context context, SharedPreferences sharedPreferences) {
    this.context = context;
    this.sharedPreferences = sharedPreferences;
  }

  public boolean isNetworkAvailable() {
    if (context == null) {
      return false;
    }
    ConnectivityManager connectivityManager = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
      Network nw = connectivityManager.getActiveNetwork();
      if (nw == null) { return false; }
      try {
        NetworkCapabilities network = connectivityManager.getNetworkCapabilities(nw);
        return network != null && (network.hasTransport(NetworkCapabilities.TRANSPORT_WIFI)
          || network.hasTransport(NetworkCapabilities.TRANSPORT_CELLULAR)
          || network.hasTransport(NetworkCapabilities.TRANSPORT_ETHERNET));
      } catch(SecurityException e) { // workaround for Android 11 bug
        NetworkInfo networkInfo = connectivityManager.getActiveNetworkInfo();
        return networkInfo != null && networkInfo.isConnected();
      }
    } else {
      NetworkInfo networkInfo = connectivityManager.getActiveNetworkInfo();
      return networkInfo != null && networkInfo.isConnected();
    }
  }

  public Flowable<Boolean> isOnlineModeAsync() {
    return Flowable.just(isOnlineMode());
  }

  public boolean isOnlineMode() {
    boolean isNetworkAvailable = isNetworkAvailable();
    boolean isOfflineModeInSettings = sharedPreferences.getBoolean(Constants.SETTINGS_OFFLINE_MODE, Constants.OFFLINE_MODE_DEFAULT_VALUE);
    if(isNetworkAvailable && !isOfflineModeInSettings) {
      return true;
    }
    return false;
  }
}

This is how it looks on the client device.

Any ideas?