Howo to get IPP endpoint - node.js

Question

I'm using the ipp npm module to send a print job from a google cloud function. I believe I have set up the printer correctly but I don't know how I'm supposed to know the exact uri for sending the print job.
The printer model is Brother MFC-L3770CDW
Here is how my settings look in the web view for the printer configuration.
And here is the function code.:
var ipp = require('ipp');
var PDFDocument = require('pdfkit');
var doc = new PDFDocument;
doc.text("Hello World");
var buffers = [];
doc.on('data', buffers.push.bind(buffers));
doc.on('end', function () {
var printer = ipp.Printer("https://10.0.0.55:443");
var file = {
"operation-attributes-tag":{
"requesting-user-name": "User",
"job-name": "Print Job",
"document-format": "application/pdf"
},
data: Buffer.concat(buffers)
};
printer.execute("Print-Job", file, function (err, res) {
if(err) {
console.log(err);
}
else{
console.log("Printed: "+res.statusCode);
}
});
console.log('executing');
});
doc.end();
console.log('finished executing');
I have tried various uris such as
https://10.0.0.55:631
https://10.0.0.55:443
https://10.0.0.55:631/ipp
https://10.0.0.55:631/ipp/printer
Sometimes I get an error like:
"Error: socket hang up
at TLSSocket.onHangUp (_tls_wrap.js:1148:19)
at Object.onceWrapper (events.js:313:30)
at emitNone (events.js:111:20)
at TLSSocket.emit (events.js:208:7)
at endReadableNT (_stream_readable.js:1064:12)
at _combinedTickCallback (internal/process/next_tick.js:139:11)
at process._tickCallback (internal/process/next_tick.js:181:9)
code: 'ECONNRESET',
path: null,
host: '10.0.0.55',
port: '631',
localAddress: undefined }"