Run ios - simulator - can not connect to server


I have an application that is working fine in a web browser.
when I try to simulate it on ios device it says that it is not connected to server.

But if I launch a browser on localhost:3000, all seems to work fine.

When I simulate the todos example it does not seem to have any issues to connect to the server.

El capitan 10.11.1
XCode 7.1
Simulator v 9.1