Thanks to your answer, I manage to understand that the port was wrong, since it's via REST, so I put back 9200.
Then I found someone with the same problem: https://groups.google.com/forum/#!topic/elasticsearch/RQGz3DdmY24
and had the same result: re-setting node discovery to true fixed my problem.
I have no idea why, and the things I wanted is to disable it since we will have another elasticsearch cluster for logging the other application on the same network.
Should I be worried, or is it standard and it would not affect the two different cluster since I specified all the nodes under the es.nodes conf?