Trying to integrate MQTT into Alexa AWS Lambda function

I am trying to get my Alexa skill to publish to an MQTT Broker in the lambda code. However it only publishes sporadically. Could somebody tell me what I am missing? Here is my code:

const Alexa = require('ask-sdk-core');
const mqtt = require("mqtt");


const protocol = 'mqtt'
const host = 'm21.cloudmqtt.com'
const port = '14297'
const clientId = `mqtt_${Math.random().toString(16).slice(3)}`

const connectUrl = `${protocol}://${host}:${port}`
console.log(connectUrl);
const client = mqtt.connect(connectUrl, {
  clientId,
  clean: false,
  connectTimeout: 4000,
  username: '****',
  password: '***',
  reconnectPeriod: 1000,
})
client.on('connect',  function(connack) { 
        console.log("MQTT Client connected " + JSON.stringify(connack));
        // publish a message to a topic
        client.publish('/IoTmanager/YardESP/Garage_close3/control', '{"status":0}', function() {
            console.log("Message is published");
            client.end(); // Close the connection when published
        });

        });
client.on('end', () => { 
  console.log('Connection to MQTT broker ended');
});
//
const LaunchRequestHandler = {
  canHandle(handlerInput) {
    return Alexa.getRequestType(handlerInput.requestEnvelope) === 'LaunchRequest';
  },
  handle(handlerInput) {
    const speechText = 'Would you like to open ur shut the Garage Door?';
    console.log("MQTT Connecting");
    /*client.on("connect", () => {
        console.log("MQTT Connected");
        client.publish("presence", "Hello mqtt");
    });*/

    //
    return handlerInput.responseBuilder
      .speak(speechText)
      .reprompt(speechText)
      .withSimpleCard('Would you like to open ur shut the Garage Door?', speechText)
      .getResponse();
  }
};
const GarageDoorCloseIntentHandler = {
  canHandle(handlerInput) {
    return Alexa.getRequestType(handlerInput.requestEnvelope) === 'IntentRequest'
      && Alexa.getIntentName(handlerInput.requestEnvelope) === 'GarageDoorCloseIntent';
  },
  handle(handlerInput) {
    const speechText = 'Closing The garage door!';
    console.log("MQTT Options: ", speechText);
    return handlerInput.responseBuilder
      .speak(speechText)
      .withSimpleCard('Closing The garage door!', speechText)
      .getResponse();
  }
};
const GarageDoorOpenIntentHandler = {
  canHandle(handlerInput) {
    return Alexa.getRequestType(handlerInput.requestEnvelope) === 'IntentRequest'
      && Alexa.getIntentName(handlerInput.requestEnvelope) === 'GarageDoorOpenIntent';
  },
  handle(handlerInput) {
    const speechText = 'Opening The garage door!';

    return handlerInput.responseBuilder
      .speak(speechText)
      .withSimpleCard('Opening The garage door!', speechText)
      .getResponse();
  }
};
const HelpIntentHandler = {
  canHandle(handlerInput) {
    return Alexa.getRequestType(handlerInput.requestEnvelope) === 'IntentRequest'
      && Alexa.getIntentName(handlerInput.requestEnvelope) === 'AMAZON.HelpIntent';
  },
  handle(handlerInput) {
    const speechText = 'You can ask me the weather!';

    return handlerInput.responseBuilder
      .speak(speechText)
      .reprompt(speechText)
      .withSimpleCard('You can ask me the weather!', speechText)
      .getResponse();
  }
};
const CancelAndStopIntentHandler = {
  canHandle(handlerInput) {
    return Alexa.getRequestType(handlerInput.requestEnvelope) === 'IntentRequest'
      && (Alexa.getIntentName(handlerInput.requestEnvelope) === 'AMAZON.CancelIntent'
        || Alexa.getIntentName(handlerInput.requestEnvelope) === 'AMAZON.StopIntent');
  },
  handle(handlerInput) {
    const speechText = 'Goodbye!';

    return handlerInput.responseBuilder
      .speak(speechText)
      .withSimpleCard('Goodbye!', speechText)
      .withShouldEndSession(true)
      .getResponse();
  }
};
const SessionEndedRequestHandler = {
  canHandle(handlerInput) {
    return Alexa.getRequestType(handlerInput.requestEnvelope) === 'SessionEndedRequest';
  },
  handle(handlerInput) {
    // Any clean-up logic goes here.
    return handlerInput.responseBuilder.getResponse();
  }
};
const ErrorHandler = {
  canHandle() {
    return true;
  },
  handle(handlerInput, error) {
    console.log(`Error handled: ${error.message}`);

    return handlerInput.responseBuilder
      .speak('Sorry, I don\'t understand your command. Please say it again.')
      .reprompt('Sorry, I don\'t understand your command. Please say it again.')
      .getResponse();
  }
};
let skill;

exports.handler = async function (event, context) {
  console.log(`REQUEST++++${JSON.stringify(event)}`);
  console.log(context);
  if (!skill) {
    skill = Alexa.SkillBuilders.custom()
      .addRequestHandlers(
        LaunchRequestHandler,
        GarageDoorCloseIntentHandler,
        GarageDoorOpenIntentHandler,
        HelpIntentHandler,
        CancelAndStopIntentHandler,
        SessionEndedRequestHandler,
      )
      .addErrorHandlers(ErrorHandler)
      .create();
  }


  const response = await skill.invoke(event, context);
  console.log(`RESPONSE++++${JSON.stringify(response)}`);

  return response;
};

I try invoking the Alexa skill and I get a proper response from/to Alexa but only sporadic messages publishing to the MQTT Broker.

Ok I have resolved my issue thanks to these two answers. How to use async functions within Alexa skill properly? and https://github.com/mqttjs/async-mqtt. It looks like the MQTT has to be wrapped in a async funtion a bit like this:

const Alexa = require('ask-sdk-core');
const mqtt = require("mqtt");

var options = {
    port: 14297,
    username: "****",
    password: "***",
    connectTimeout: 3000,
    debug: true
};

var client;

LaunchRequestHandler = {
    canHandle(handlerInput) {
        return Alexa.getRequestType(handlerInput.requestEnvelope) === 'LaunchRequest';
    },
    handle(handlerInput) {
        const speechText = 'Would you like to open ur shut the Garage Door?';


        return handlerInput.responseBuilder
            .speak(speechText)
            .reprompt(speechText)
            .withSimpleCard('Would you like to open ur shut the Garage Door?', speechText)
            .getResponse();
    }
};
const GarageDoorCloseIntentHandler = {
    canHandle(handlerInput) {
        return Alexa.getRequestType(handlerInput.requestEnvelope) === 'IntentRequest' &&
            Alexa.getIntentName(handlerInput.requestEnvelope) === 'GarageDoorCloseIntent';
    },
    async handle(handlerInput) {
        const speechText = 'Closing the garage door!';
        client = await mqtt.connectAsync('mqtt://m21.cloudmqtt.com', options);
        try {
            await client.publish("wow/so/cool", "It works!");
            // This line doesn't run until the server responds to the publish
            await client.end();
            // This line doesn't run until the client has disconnected without error
            console.log("Done");
        } catch (e) {
            // Do something about it!
            console.log(e.stack);
            process.exit();
        }
        return handlerInput.responseBuilder
            .speak(speechText)
            .withSimpleCard('Closing the garage door!', speechText)
            .getResponse();
    }
};
const GarageDoorOpenIntentHandler = {
    canHandle(handlerInput) {
        return Alexa.getRequestType(handlerInput.requestEnvelope) === 'IntentRequest' &&
            Alexa.getIntentName(handlerInput.requestEnvelope) === 'GarageDoorOpenIntent';
    },
    async handle(handlerInput) {
        const speechText = 'Opening the garage door!';
        client = await mqtt.connectAsync('mqtt://m21.cloudmqtt.com', options);
        try {
            await client.publish("wow/so/cool", "It works!");
            // This line doesn't run until the server responds to the publish
            await client.end();
            // This line doesn't run until the client has disconnected without error
            console.log("Done");
        } catch (e) {
            // Do something about it!
            console.log(e.stack);
            process.exit();
        }

        return handlerInput.responseBuilder
            .speak(speechText)
            .withSimpleCard('Opening The garage door!', speechText)
            .getResponse();
    }
};
const HelpIntentHandler = {
    canHandle(handlerInput) {
        return Alexa.getRequestType(handlerInput.requestEnvelope) === 'IntentRequest' &&
            Alexa.getIntentName(handlerInput.requestEnvelope) === 'AMAZON.HelpIntent';
    },
    handle(handlerInput) {
        const speechText = 'You can ask me to open or shut garage door!';

        return handlerInput.responseBuilder
            .speak(speechText)
            .reprompt(speechText)
            .withSimpleCard('You can ask me to open or shut garage door!', speechText)
            .getResponse();
    }
};
const CancelAndStopIntentHandler = {
    canHandle(handlerInput) {
        return Alexa.getRequestType(handlerInput.requestEnvelope) === 'IntentRequest' &&
            (Alexa.getIntentName(handlerInput.requestEnvelope) === 'AMAZON.CancelIntent' ||
                Alexa.getIntentName(handlerInput.requestEnvelope) === 'AMAZON.StopIntent');
    },
    handle(handlerInput) {
        const speechText = 'Goodbye!';

        return handlerInput.responseBuilder
            .speak(speechText)
            .withSimpleCard('Goodbye!', speechText)
            .withShouldEndSession(true)
            .getResponse();
    }
};
const SessionEndedRequestHandler = {
    canHandle(handlerInput) {
        return Alexa.getRequestType(handlerInput.requestEnvelope) === 'SessionEndedRequest';
    },
    async handle(handlerInput) {
        // Any clean-up logic goes here.
        client = await mqtt.connectAsync('mqtt://m21.cloudmqtt.com', options);
        try {
            await client.publish("wow/so/cool", "It works!");
            // This line doesn't run until the server responds to the publish
            await client.end();
            // This line doesn't run until the client has disconnected without error
            console.log("Done");
        } catch (e) {
            // Do something about it!
            console.log(e.stack);
            process.exit();
        }
        return handlerInput.responseBuilder.getResponse();
    }
};
const ErrorHandler = {
    canHandle() {
        return true;
    },
    handle(handlerInput, error) {
        console.log(`Error handled: ${error.message}`);

        return handlerInput.responseBuilder
            .speak('Sorry, I don\'t understand your command. Please say it again.')
            .reprompt('Sorry, I don\'t understand your command. Please say it again.')
            .getResponse();
    }
};
let skill;

exports.handler = async function(event, context) {
    console.log(`REQUEST++++${JSON.stringify(event)}`);
    if (!skill) {
        skill = Alexa.SkillBuilders.custom()
            .addRequestHandlers(
                LaunchRequestHandler,
                GarageDoorCloseIntentHandler,
                GarageDoorOpenIntentHandler,
                HelpIntentHandler,
                CancelAndStopIntentHandler,
                SessionEndedRequestHandler,
            )
            .addErrorHandlers(ErrorHandler)
            .create();
    }


    const response = await skill.invoke(event, context);
    console.log(`RESPONSE++++${JSON.stringify(response)}`);


    return response;
};