Kibana did not load properly check the server output for more information - status 503

Hi, I am having some issues with Kibana whenever I try to access it within an application, but it always works if I use the URL from kibana.yml. I can not find any 503 messages in neither kibana nor IIS logs. Any ideas why this is failing and how can I get more info about this error?

Kibana

Mind expanding on this? What do you mean by accessing it within an application? And what URL within the kibana.yml?