WSS over Secure SSL connection fails only on FireFox with error 1006

My website runs on https/ssl (valid CA certificate) on IIS 10.0 (iisnode 0.2.21) / node/express. I am using a websocket server on top of https server (same port)

However the websocket connection works very well for CHrome and IE11. It fails only for Firefox (version 80) with error code 1006 (error details)

in Inspector / Network console, it gives the following errorerror as shown in network under inspector console

In the web.config file, I have added the following line <webSocket enabled="false"/>

app.js code is as below:

var cors = require('cors');
var createError = require('http-errors');
var cookieParser = require('cookie-parser');
const https = require("https");
// var app = express();
var app = require('express-ws-routes')();

.....

var wsRouter = require("./routes/wsRoute"); // route for Websocket

....
app.use('/ws', wsRouter);

....
app.listen(process.env.PORT || 443);

In my Websocket route, I use the following code

router.websocket('/', function(info, cb,  next) {
    
    var connid = info.req.query.connid;
    var pgid = info.req.query.pageid;

    cb(function(socket) {   
        // socket is connected   
        socket.send(JSON.stringify({'response_type':'WSConnActive',
                            'response':{"status":"success","details":"Welcome Message","reqOrigin":"Home","welcomeMsg":'Hello '+usr+', Welcome! you are now connected!'}}));

....
 socket.on('message', function incoming(message) {  // handle message }

socket.on("close", function socketClose(ws){
            console.log(info.req.query.usr+" closed session at "+moment().format("YYYY-MM-DD HH:mm:ss"));
            var usrClose = info.req.query.usr;
...}
});  });

At the client end I connect var socket = new WebSocket('wss://<host>:443/ws?request_type=init&usr='+UserID+'&connid='+connectTime+'&pageid='+page_ID);

All this works as expected for Chrome and IE11 except firefox

I am not sure where the issue is.. any help is appreciated!