JavaScript file does not load, the site takes a long time to open. How to open a port in cloud9?

Question

JavaScript

Loading file ...c9users.io:35729/livereload.js stops with a timeout.
Because of this, the site opens for a very long time, there is an included JavaScript in the index file:
In fact, it is not at the root.
I think there's something I can't understand. I read about livereload, but still did not find the answer.
Searched in this way in Google 35729/livereload.js
In the results they write this
https://github.com/linnovate/mean/issues/448
I had the same problem where it would take a minute or so to load. I'm still running on the development environment. The console showed a timeout when trying to access livereload.js on port 35729. I solved it by adding port 35729 (set Source to My IP) to my Security Group -> Inbound ports in EC2. Now it runs very fast.
But how to open port in ubuntu cloud9.io virtule?
Help