Running multiple Node applications on same ip address with different ports , only port 3000 is working

I have been running a static ip address of 10.100.40l.206 on a linux box.

Then I have a Node application in which I usually run with pm2 , but it works without.

I run this as port 3000 ( which i suppose is something common i guess)

so This works

http://10.100.40.206:3000/#!/view1

So I uploaded another application and I have it in www file as port 3500

So even If i run with

 node ./bin/www  

or

 pm2 start www  

Neither work, and I have even stopped the other node site. So locally it works great. Is it the port thing?

in my www file i have this code

var port = normalizePort(process.env.PORT || '3500');
app.set('port', port);

via Jeremy Miller