I have a droplet on DigitalOcean with elasticsearch properly running, I have another installation (on a different server) of wordpress with elasticpress that keeps sending this error: <strong>There is a problem with connecting to your Elasticsearch host. ElasticPress can try your host again, or you may need to change your settings.</strong> I'm using the IPv4 of the digitalocean droplet and port 9200 in the WP-config file, to define EP_HOST. Do I need a proxy server or what is missing? I've followed many tutorials with no success.