Reactjs – WebSocket connection to 'wss://domain:3000/ws on production server. No websocket was actually installed

I am getting this error:

WebSocketClient.js:13 WebSocket connection to ‘wss://domain:3000/ws’ failed:

However, I have not set up the Websocket, it was outomatically added with create-react-app. I have read somewhere that it is Hot Reload and should disappear in production build. But after I build the project (and start it with npm start from build folder ) in production server I still get the Websocket active and it gives me the error. (To add I have checked all the installed modules this websocket comes with Webpack and no other module)local websocket request

My nginx config:

server {
    listen 80;
    listen [::]:80;

    server_name domain.com www.domain.com;

    location / {
        proxy_pass http://127.0.0.1:3000;
    }
    
    location /api/ {
        proxy_pass http://127.0.0.1:9999;
    }
    location /ws {
        proxy_pass http://127.0.0.1:3000;
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection "Upgrade";
    }

        location /wss {
        proxy_pass http://127.0.0.1:3000;
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection "Upgrade";
    }
}

I did add location ws / and location wss / in my nginx config file. And I did try to add WDS_SOCKET_PORT= 0 or WDS_SOCKET_PORT = 3000 (my front end host) Nothing worked. I’m stuck here and dont know how to get rid of this.