使用Node.js通过MQTT连接到Google Cloud IoT时出现问题

我正在尝试创建一个将连接到Google Cloud IoT Core的MQTT客户端，但是由于某种原因，它根本无法连接。这是我到目前为止的

mqtt = require("mqtt")
fs = require("fs")
var jwt = require('jsonwebtoken');


const projectId = "my-project" 
const deviceId = "my-device" 
const registryId = "my-degistry" 
const region = "us-central1"
const algorithm = "RS256"
const privateKeyFile = "./rsa_private.pem"
const mqttBridgeHostname = "mqtt.googleapis.com"
const mqttBridgePort = 8883
const messageType = "events"

//The mqttClientId is a unique string that identifies a particular device. 
//For Google Cloud IoT Core, it must be the format below
const mqttClientId = `projects/${projectId}/locations/${region}/registries/${registryId}/devices/${deviceId}`
const mqttTopic = `/devices/${deviceId}/${messageType}`;


const createJwt = (projectId, privateKeyFile, algorithm) => {
    // Create a JWT to authenticate this device. The device will be disconnected
    // after the token expires, and will have to reconnect with a new token. The
    // audience field should always be set to the GCP project id.
    const token = {
      iat: parseInt(Date.now() / 1000),
      exp: parseInt(Date.now() / 1000) + 20 * 60, // 20 minutes
      aud: projectId,
    };
    const privateKey = fs.readFileSync(privateKeyFile);
    return jwt.sign(token, privateKey, {algorithm: algorithm});
  };

//Username field is ignored in Cloud IoT Core, but it must be set to something
//Password field sends a JWT (javascript web token) to authorize the device
//mqtts protocol causes library to connecti using SSL, which is required for IoT Core
const connectionArgs = {
    host: mqttBridgeHostname,
    port: mqttBridgePort,
    clientId: mqttClientId,
    username: "unused",
    password: createJwt(projectId, privateKeyFile, algorithm),
    protocol: "mqtts",
    secureProtocol: "TLSv1_2_method"
}

const client = mqtt.connect(connectionArgs)

client.on("connect", (connected)=>{
    console.log("Attempting to connect")
    if (!connected) {
        console.log("Client failed to connect")
    } else {
        console.log("Client is connected!")
    }
})

client.on("error", err => {
    console.log(err)
    setTimeout(( ()=> {  
        console.log('Terminating process')
        return process.kill(process.pid);
    }), 1000);
})

client.on("packetsend", (payload) => {
    console.log("Payload has been sent")
    return process.kill(process.pid)
})

client.on("packetreceive", packet => {
    console.log("Killing")
    //return process.kill(process.pid)
})

client.on("reconnect", ()=>{
    console.log("Attempting a reconnect")
    //return process.kill(process.pid)
})

client.on("close", ()=>{
    console.log("A disconnect occurred")
    // return process.kill(process.pid)
})

client.on("offline", () => {
    console.log("Client is offline")
    //return process.kill(process.pid)
})

尝试连接服务器时没有出现任何错误。换句话说，一切似乎都在正确地进行身份验证，并且我没有收到任何错误消息，但是客户端从未连接到云，而是反复尝试以无休止的循环重新连接（这就是为什么我包含杀死脚本的代码的原因）。我尝试浏览Google Cloud故障排除页面，但似乎没有任何帮助。使用Cloud SDK时，如建议的指南所示，我没有收到任何类型的错误消息或有用的信息。

我已经通过防火墙打开了8883端口，以防万一这是问题所在，但事实并非如此。

我将此代码基于Google的一些指南，并基于此指南。我有一个注册表，项目和设备，都设置了正确的RSA密钥。

所以我不太确定如何进行！如果还有其他有用的信息，请告诉我。

谢谢。