websocket was blocked by Nginx server

I have a nginx server sitting before a java application server.  The java application uses some websocket to connect to the clients.

I followed this article to update the nginx configurations. However, the application still not working properly. After I log into the application for a few seconds, i was kicked out from the web application. Any idea of this?

thanks.

https://chrislea.com/2013/02/23/proxying-websockets-with-nginx/



server {
        listen       80 default_server;
        listen       [::]:80 default_server;
        # server_name  localhost;
        # root         /usr/share/nginx/html;

        server_name  localhost;
        #root         /usr/share/nginx/html;

        # Load configuration files for the default server block.
        include /etc/nginx/default.d/*.conf;

        location / {
        proxy_pass http://10.104.0.104;
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection "upgrade";
        proxy_set_header Host $host;
        }