react-native-zeroconf - mdns discovery in android emulator

Question

I am new to React-Native and mobile development. I am trying to program a MQTT client app.

The app is running on an Android Emulator and it is supposed to find a MQTT Broker running on an ESP8266 D1 mini in my local network. The problem is that the emulator has no direct access to my local network.

I set up a network bridge from my Host Ethernet adapter to the virtual Ethernet Adapter of the emulator and gave him a static IP. In the emulator I can access the internet, but can't connect for example to my routers web interface or other devices in my local network.

How can I configure the emulator so the app I am runnng on it can discover mDNS services on my local network?

I am quite unexperienced with emulators and mobile development, but I don't think using port forwarding will help here, since I want to test the mDNS discovery. Am I wrong?

The MQTT Broker is running, I can connect via MQTT Explorer from my localhost.

This is my React-Native code:

import React, {useState, useEffect} from 'react';
import {View, StyleSheet, Text} from 'react-native';
import init from 'react_native_mqtt';
import Zeroconf from 'react-native-zeroconf';
import AsyncStorage from '@react-native-async-storage/async-storage';

import Flame from '../components/Flame';

init({
  size: 10000,
  storageBackend: AsyncStorage,
  defaultExpires: 1000 * 3600 * 24,
  enableCache: true,
  reconnect: true, // Enable reconnection
  sync: {},
});

function HomeScreen() {
  // State for temperature and alert
  const [temperature, setTemperature] = useState(0);
  const [alert, setAlert] = useState('');
  const zeroconf = new Zeroconf();

  zeroconf.on('error', error => {
    // log the error
    console.log('Zeroconf Error:', error);
  });

  zeroconf.on('found', service => {
    // log the service
    console.log('Zeroconf scan successful:', service);

    const {addresses, port} = service;

    // Use the discovered MQTT broker address
    const options = {
      host: addresses[0], // Use the discovered MQTT broker address
      port: port,
      clientId: 'id_' + parseInt(Math.random() * 100000),
    };

    const client = new Paho.Client(
      options.host,
      options.port,
      options.clientId,
    );

    function onConnect() {
      console.log('Connected to MQTT broker');
      client.subscribe('temperature', {qos: 0});
      client.subscribe('alert', {qos: 0});
    }

    function onConnectionLost(responseObject) {
      if (responseObject.errorCode !== 0) {
        console.log('onConnectionLost: ' + responseObject.errorMessage);
      }
    }

    function onMessageArrived(message) {
      console.log('onMessageArrived: ' + message.payloadString);

      if (message.destinationName === 'temperature') {
        setTemperature(parseFloat(message.payloadString));
      } else if (message.destinationName === 'alert') {
        setAlert(message.payloadString);
      }
    }

    useEffect(() => {
      client.onConnectionLost = onConnectionLost;
      client.onMessageArrived = onMessageArrived;
      client.connect({onSuccess: onConnect, useSSL: false, timeout: 3});

      // Clean up and disconnect from MQTT when the component unmounts
      return () => {
        if (client.isConnected()) {
          client.disconnect();
        }
      };
    }, []);
  });
  // Discover the MQTT broker using Zeroconf
  zeroconf.scan('mqttbroker._tcp', 'local.');

  return (
    <View style={styles.container}>
      <Flame />
      <Text style={styles.text}>{temperature}°C</Text>
    </View>
  );
}

const styles = StyleSheet.create({
  container: {
    flex: 1,
    justifyContent: 'center',
    alignItems: 'center',
    backgroundColor: '#000',
  },
  text: {
    color: '#fff',
    fontSize: 25,
    position: 'absolute',
    transform: [{translateY: 100}],
  },
});

export default HomeScreen;

When running the app the following error is loged:

 LOG  Zeroconf Error: [Error: Starting service discovery failed with code: 0]

EDIT:

On my localhost I checked firewall rules inbound and outbound for mdns, both are allowed!

I also added rules for

MQTT on port 1883 - tcp and udp, inbound and outbound (only privat network)

and

mDNS on port 5353 - udp, inbound and outbound (only privat network)