Cannot reach Cordova app with browser

I want to use a Cordova application that is running on a remote server (with ip address e.g 111.111.111.111) listening on port 4444. When I try netstat -tlpn on that server, I get

tcp6       0      0 :::4444        :::*       LISTEN      923/server.js

So the port is listening. However, if I type on my browser 111.111.111.111:4444 I get ERR_EMPTY_RESPONSE. The same thing with 111.111.111.111:4444/app. Why can't I reach the app? (I have not developed the application, but I have access to the code)

via SegFault