Nginx: connect() failed while connecting to upstream

Spam in error.log:

2017/05/07 16:51:50 [error] 30504#0: *7089 connect() failed (111: Connection refused) while connecting to upstream, client: 169.54.244.93, server: iix.se, request: "GET / HTTP/1.1", upstream: "http://[::1]:8001/", host: "phoenix.iix.se"

In your nginx configuration, replace hostnames with ip-addresses