How to configure expressjs/socketio webchat on ubuntu server

I wasn't sure if this is appropriate on the Ubuntu exchange or here but it is mostly code related i believe.

So I have created a neat working little web-chat application using socket.io which I've been developing on my Win10 pc using Git-bash and running it on my localhost with node.js and everything has been working just fine.

Thus I have come to a point where I would like to try out my app on my web-server.

Lets get more detailed what my Problems are:

1. I am unsure of how my server.js file should listen or open up the ports so to speak. I have tried looking in the sockets.io chat example and tried their method yet the '../..' module leaves me confused.
2. Following the express.js site tutorial I actually get my server to respond listening on port 3000 yet my website returns the no socket.io/socket.io.js found.
3. this and this just lead to another localhost tutorial

In Short I have come to the point where when i do node server.js It seems to start listening here's the code to that part:

  var express = require('express');
    var http = require('http');
    var app = express();
    var server = http.createServer(app);
    var io = require('socket.io').listen(server);
    var port = process.env.PORT || 3000;

    app.get ('/', function(req,res) {
     res.sendFile(__dirname + '/index.html');
    });

    app.use("/static", express.static('./static/'));
    server.listen(3000);

But now the problem is is that my html file cannot seem to find the socket.io/socket.io.js file, even though i have installed sockets.io, i consulted to this stack question which should fix it, but it didnt thus leads me to believe theres a thicker more server side issue?

Versions i am using:
  express: **4.16.4**;
  node   : **10.15.0**;
  npm    : **6.4.1**;
  socket : **2.2.0**;

EDIT: Added my html code snips

html

  <script src="/socket.io/socket.io.js"></script>
        <script src="https://code.jquery.com/jquery-1.11.1.js"></script>
        <script src="static/index.js"></script>