After a while (couldn't tell how long), Kibana loses connection to the ES cluster (tested with two installations, one locally on the ELK stack, one from a remote machine. I am getting these error messages:
2017/02/28 12:51:25 warn 19741#0: *335 upstream server temporarily disabled while connecting to upstream, client: 192.168.1.120, server: n2, request: "GET /bundles/kibana.style.css?v=9910 HTTP/1.1", upstream: "http://[::1]:5601/bundles/kibana.style.css?v=9910", host: "XXXXX:8888", referrer: "http://XXXXX:8888/app/kibana"
2017/02/28 12:51:57 [info] 19741#0: 332 kevent() reported that client prematurely closed connection, so upstream connection is closed too while sending request to upstream, client: 192.168.1.120, server: n2, request: "POST /elasticsearch/filebeat-/_field_stats?level=indices HTTP/1.1", upstream: "http://127.0.0.1:5601/elasticsearch/filebeat-*/_field_stats?level=indices", host: "XXXXX:8888", referrer: "http://XXXXX:8888/app/kibana"
where 192.168.1.120 is the PC I'm on, and XXXXX is an OpenBSD6.0 machine that's forwarding Port 8888 ro localhost:5601.
Restarting Kibana is giving me access again.
Where should I begin to dig?