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Excel Javascript Add-in Deployment On Local Network

I have developed an Excel Javascript Add-in on my machine using the yeoman generator. The add-in itself works fine when I start it up on my client with npm start. I can use the add-in on any port I want provided I change all the ports in the config files etc. However, we now want to delpoy this add-in on our local server to make it available to several users.
I have noticed that every time I change the location of the project e.g. from my machine to the server the application will start up but Excel will give me the error message "ADD-IN ERROR Sorry, we can't load the add-in. Please make sure you have network and/or Internet connectivity. Click "Retry" once you are back online". My work around for now is to create a new app on the server and copy the html, js and css file to the taskpane folder. When I now start up the new app it'll work fine.
For the second issue I haven't found a solution/understood the behaviour. When I create an app with the yeoman generator on our server (MS server 2019) and start it up it can be reached via e.g. localhost:3000 on the server but not via :3000 or :3000. It runs fine when I access it from the server itself.
I have opened the inbound and outbound port 3000 on the server to allow https communication. In a next step I added the manifest to the windows 365 admin console and added myself as user. When I open Excel from my machine (client side) the excel add-in will be available in the insert ribbon but won't load and I get the same error message as described above "ADD-IN ERROR Sorry, we can't load the add-in. Please make sure you have network and/or Internet connectivity. Click "Retry" once you are back online"
The following troubleshooting steps have been performed. I checked whether I can reach the add-in url via web browser but the connection timed out. When I check on the server side whether the app is listening I get the below result.
TCP 127.0.0.1:3000 0.0.0.0 Listening 40776
I'm not sure but I think the app should list on e.g. 0.0.0.0:3000 to capture inbound traffic from the client side. Is there a way to change this add-in (app) behaviour on the server when creating/starting up the app with the yeoman generator? I have checked the webpack.config.js file but I couldn't find any way to change that behaviour.
Any idea/help is appreciated.
Thanks!

I believe this is precisely the intended configuration of the yeoman development environment. It spins up the webpack dev (NodeJS) server, which by default only listens to the localhost / loopback address.
From here:
https://webpack.js.org/configuration/dev-server/#devserverhost
It looks like you could hand modify your webpack.config.js file to include a
host: '0.0.0.0' entry under the devServer listing.
The other item you might need to change is
https://webpack.js.org/configuration/dev-server/#devserverallowedhosts
As I believe this defaults to 'auto' which would only allow connections from the local computer.

What does io.connect('http://localhost:4000) mean?

I am building an application using react.js and socket.io, I have my backend code for the socket.io server in one folder and the client/ frontend react.js code in a separate folder. I have it set up to where the server is listening on local host:4000 and the client is listening on 3000, I have connected the front end and back end in my app.js using this line of code..
const socket = io.connect('http://localhost:4000');
I am curious as to what this means. does it mean that when I deploy my website that it will be hosting my server from my computer? Does it mean that it will be hosting the sockets from the client's computers? is the localhost:4000 used for testing purposes and will need to be changed later upon deployment of the website? If none of these are correct, any explanation would be greatly appreciated. If my code is fine the way it is and will not need to be changed upon deployment of my website, please let me know.
Thank you to anyone who can help!!!

does it mean that when I deploy my website that it will be hosting my server from my computer?
It means it will try to connect to a Socket.io server running on the same computer as the browser is running on.
This will usually fail. (Your development environment is an exception because you are running both browser and server on the same computer).
is the localhost:4000 used for testing purposes and will need to be changed later upon deployment of the website?
Yes.

Yes, you will need to change it when you deploy it to your site.
'http://localhost:4000' is an absolute reference meaning it will auto resolve to the localhost environment. It is also advisable to switch to https for a more secure connection.

webRTC nodejs not working after deployment in vercel

I have developed and deployed nodejs webrtc still not working
after deployment
Design not working
Live video communication is also not working
this is the live link click here
this is git repo link click here

The demo signaling server for that (long since deprecated) package is no longer running at that address anymore. Run your own.

Your socket isn't connecting. You need to setup your cors with the name of the frontend website.

How to connect frontend and backend on domain

I don't really have experience with backend and how things work together. I have created a simple live message sending app with node.js and socket.io. When I host a static web server on my machine (http-server which runs on local port using node.js) my app works perfectly fine but when I upload it on my host or github pages just for test, the backend doesn't seem to work. I uploaded all my files with an FTP program and the frontend loads fine but the backend doesn't. Do I have to know something like Django or ASP.NET to make these work on my host?
EDIT: One more thing, first line in my server.js is const io = require('socket.io')(3000)and in my script.js - const socket = io('http://localhost:3000')where 3000 and localhost:3000 stands for local host in my machine. What do i need to put instead of these?

You probably need to install and setup Node.js on your server, contact yout hosting provider for node installation if the option isn't available in yout cPanel.

How to give the server port to client

I have a node server with several node projects. I use nginx to get them all responding on port 80. Now, this works for the initial http request. For the websockets, I need to use the direct server port. To keep everything alive while developing I would like to try this, projects will have a dev and live version. Once de dev is stable, I will copy it to the live folder. The live folder is runned by a systemctl script where I define a difrent port to the live version so I can dev without taking the live down. The problem I encounter now is, how can I get the running server port in my client side Javascript so that the dev page connect to the dev port and visa versa?
currently I'm only using express, socket.io and mysql. I have no further npm packages installed. I searched allot but there is not to mush I can find. I found how to connect the socket to the page url but I cannot use that because that URL will always be on port 80. Further I found allot of huge packages that has no use for me since the original page is just static, the dynamics all run over websockets.
Is there any way to parse the port number in the clients .js file like I could do fairly easy in php? And if so, what would be the most efficient way. I could let javascript check if the page uses the live or dev URL but I would prefer not to hardcode my dev URL into JS where it is for everyone to see.

run a third node.js socket.io server program, all your clients connect to this server first.
In this simple node.js program, determine the type of clients by any means. e.g. different user id for dev/production users
send the server url and port to your client according to its type (dev or production)
you may also use this technique to separate your users to different production servers.