Hello everybody!
I am a new and excited nginx user and I just had to hit a problem complex enough for me to post a message here hoping to get some help.

OS: OpenBSD 5.5 amd64
nginx -v: nginx version: nginx/1.4.7

nginx.conf:

user www;
worker_processes 10;
error_log /var/log/nginx/error.log error;
worker_rlimit_nofile 1024;
events {
worker_connections 800;
}
http {
include mime.types;
default_type application/octet-stream;
index index.jsp;
keepalive_timeout 4;
upstream shipmaticacluster {
server 10.0.0.10:8080;
server 10.0.0.11:8080;
}
server {
server_tokens off;
access_log /var/log/nginx/proxy.log;
location / {
proxy_pass http://shipmaticacluster;
}
}
}


Here is the problem: if the following is used:
proxy_pass http://10.1.1.10:8080;
or this is used:
proxy_pass http://10.1.1.11:8080;
then the requests are executed and the proxy log has this in it:

192.168.0.13 - - [16/Jun/2014:21:22:56 -0400] "GET /Shipmatica/ HTTP/1.1" 200 11118 "-" "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:16.0) Gecko/20100101 Firefox/16.0"

and that is great!

However when I use upstream cluster settings:

proxy_pass http://shipmaticacluster;

then the request executes a long time until it expires or until I hit escape in the browser and then these lines are printed into the proxy log:

192.168.0.13 - - [16/Jun/2014:23:03:26 -0400] "GET /Shipmatica HTTP/1.1" 499 0 "-" "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:16.0) Gecko/20100101 Firefox/16.0"

and info log:

2014/06/16 23:03:26 [info] 29349#0: *1 kevent() reported that client prematurely closed connection, so upstream connection is closed too while connecting to upstream, client: 192.168.0.13, server: , request: "GET /Shipmatica HTTP/1.1", upstream: "http://10.0.0.10:8080/Shipmatica", host: "192.168.0.28"


I have gone through about 5 or 6 hours of internet searches and experiments by now, looked at the system log files and payed attention to pflog, no results anywhere, nothing is found in the OS log files, pf doesn't block any traffic. I switch back to the specific IP address in the proxy_pass and the requests flow through just fine.

This is as far as I can go without some help, I hope somebody has insights on this issue.

Thank you!
Roman