Elasticsearch failed connection in linux setup

[mrtuvn]

Every up but when access to magento backend to change
Catalog Search engine from MYSQL to Elasticsearch

Result when i try click on button "Test Connection" Button's label return failed
i can access localhost:9200 from browser
everything set or i need manually re-setup elasticsearch

Reference
follow this but not get any luck
https://devdocs.magento.com/guides/v2.3/config-guide/elasticsearch/es-config-apache.html