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Connection loop with MQTT

Hi, I have a problem with the connection of the MQTT Client to the SAP IoT cockpit broker in a secured environment. (node.js / mqtt Skript, see below)

At home it's working fine. But if I try the skript in the company environment it's stuck in a connection loop.

Client offline
Client close
Client reconnect
Client close
Client reconnect

How can I catch the error? We opend the MQTT TCP Port 8883 but was that even necessary?


const mqtt = require("mqtt");
var connectOptions = {
  keepalive: 10,
  clientId: deviceAlternateId,
  clean: true,
  reconnectPeriod: 2000,
  connectTimeout: 2000,
  cert: fs.readFileSync(certFile),
  key: fs.readFileSync(certFile),
  passphrase: fs.readFileSync(secretPasswordFile).toString(),
  rejectUnauthorized: false

var Client = mqtt.connect("mqtts://<SAP-IoT AE Service>:8883", connectOptions);

Client.on("connect", function () {
  console.log("Client connect");

Client.on("error", function (err) {
  console.log("Client ERROR : ");

Client.on("offline", function () {
  console.log("Client offline");

Client.on("reconnect", function () {
  console.log("Client reconnect");

Client.on("close", function () {
  console.log("Client close");


Thank you for any help

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1 Answer

  • Best Answer
    Posted on Oct 10, 2018 at 09:58 AM

    I suggest you add this tag: SAP Cloud Platform Internet of Things for the Cloud Foundry environment as this is about the device connectivity.

    I would guess that in your secured network the router might be configured to not let traffic on the port 8883 pass. Or you might have a proxy configured and the proxy does not let this traffic through. I suggest you check with the people who operate this secure network. Workaround 1 would be to use REST instead (especially for the blocked port). Workaround 2 is to use a mobile phone hotspot (if its just for demo or prototyping).

    At SAP our IT has setup additional network segments called SAP-Guest/SAP-Internet that allow a direct internet connection without proxy, do not allow reaching the Intranet and also allow ports required for MQTT. IoT devices are whitelisted based on their MAC address.

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