How to fix Node SOAP service when it thorws Parsing WSDL error

I have a NodeJS server that also has a SOAP service running in the app.js directory.

The service works fine when I test it with PostMan (when I perform a POST request against the endpoint) but it throws an error when a client tries to access it with a PHP client.

Error:

Parsing WSDL: Couldn't load from 'https://{URL}/soap/wsdl.

As I understand the problem is that the endpoint works fine, but there is no WSDL description attached?

If this is the case, how do I "attach" the WSDL description to this enpoint?

app.js content:

import "babel-polyfill";
import app from './config/express';
import config from './config/config';
import bodyParser from 'body-parser'
import soap from 'soap'

let xml = require('fs').readFileSync('./REDE.wsdl', 'utf8');
let myService = {
      RealEstateDataExchange: {
          RealEstateDataExchangePort: {

              getObjectIdsByStatus: function(args, callback) {
                // do something and get result
                // call callback with result like so:
                // callback( result );
              }
          }
      }
  };

app.use(bodyParser.raw({type: function(){return true;}, limit: '5mb'}));
app.listen(config.port, () => {
  console.info(`Server started on port ${config.port}`);
  soap.listen(app,'/soap/wsdl',myService,xml);
});

export default app;

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