Nginx error recv() failed (104: Connection reset by peer) – Plesk

Since a couple of days ago, I’m getting some errors on my server. I use CentOS 6.5 with Parallels 12.0.18, Apache server to serve dynamic content and Nginx as proxy to serve static content.

At first, I was getting the following error:

[error] 29951#0: *5138862 upstream timed out (110: Connection timed out) while reading response header from upstream, client: 89.7.24.108, server: , request: "GET /page/2/ HTTP/1.1", upstream: "http://ip:7080/page/2/", host: "domain.es", referrer: "http://domain.es/"

Then, I changed some configuration, like increasing MaxClients on my “httpd.conf” file and this lines to my /etc/nginx/conf.d/timeout.conf file:

proxy_connect_timeout       600;
proxy_send_timeout          600;
proxy_read_timeout          600;
send_timeout                600;

It all seemed to be working fine until I got the same errors again, along with a new one:

[error] 15228#0: *130292 recv() failed (104: Connection reset by peer) while reading response header from upstream, client: 89.130.25.154, server: domain.com, request: "GET / HTTP/1.1", upstream: "http://127.0.0.1:7080/", host: "domain.com"

I have two different websites on the same server. That’s why you see two different hosts in there.

Here’s the problem: when I got these errors, I got a “502 Bad Gateway” and the server becomes so slow that I can’t even log in using the SSH terminal. I can only fix it temporally by resetting the httpd service.

I know there are other topics similar to this one, but all I found were problems with PHP-FPM, which I don’t use.

Here’s my Nginx configuration file:
user nginx;
worker_processes 16;

error_log  /var/log/nginx/error.log;

events {
    worker_connections  1024;
}

http {
server_names_hash_max_size 2048;
server_names_hash_bucket_size 512;

server_tokens off;

include    mime.types;
default_type  application/octet-stream;

sendfile on;
tcp_nopush on;
tcp_nodelay on;
keepalive_timeout  10;

# Gzip on
gzip on;
gzip_vary on;
gzip_min_length 10240;
gzip_proxied expired no-cache no-store private auth;
gzip_buffers 4 32k;
gzip_types text/plain text/css application/json application/x-javascript text/xml application/xml application/xml+rss text/javascript application/javascript text/x-js;
gzip_disable "MSIE [1-6].";

# Other configurations
ignore_invalid_headers on;
client_max_body_size    8m;
client_header_timeout  3m;
client_body_timeout 3m;
#send_timeout     3m;
connection_pool_size  256;
client_header_buffer_size 4k;
large_client_header_buffers 4 32k;
request_pool_size  4k;
output_buffers   4 32k;
postpone_output  1460;

# Cache most accessed static files
open_file_cache          max=10000 inactive=10m;
open_file_cache_valid    2m;
open_file_cache_min_uses 1;
open_file_cache_errors   on;

# virtual hosts includes
include "/etc/nginx/conf.d/*.conf";
}

Here’s my Nginx vhost file:
server {
listen ip:80 default_server;

server_name domain.es;
server_name www.domain.es;
server_name ipv4.domain.es;

client_max_body_size 128m;

root "/var/www/vhosts/domain.es/httpdocs";
access_log "/var/www/vhosts/system/domain.es/logs/proxy_access_log";
error_log "/var/www/vhosts/system/domain.es/logs/proxy_error_log";

if ($host ~* ^www.domain.es$) {
    rewrite ^(.*)$ http://domain.es$1 permanent;
}

location / {
    proxy_pass http://82.194.74.41:7080;
    proxy_set_header Host             $host;
    proxy_set_header X-Real-IP        $remote_addr;
    proxy_set_header X-Forwarded-For  $proxy_add_x_forwarded_for;
    access_log off;
}

location @fallback {
    proxy_pass http://ip:7080;
    proxy_set_header Host             $host;
    proxy_set_header X-Real-IP        $remote_addr;
    proxy_set_header X-Forwarded-For  $proxy_add_x_forwarded_for;
    access_log off;
}

location ~ ^/plesk-stat/ {
    proxy_pass http://ip:7080;
    proxy_set_header Host             $host;
    proxy_set_header X-Real-IP        $remote_addr;
    proxy_set_header X-Forwarded-For  $proxy_add_x_forwarded_for;
    access_log off;
}

location ~ ^/(.*.(ac3|avi|bmp|bz2|css|cue|dat|doc|docx|dts|exe|flv|gif|gz|htm|html|ico|img|iso|jpeg|jpg|js|mkv|mp3|mp4|mpeg|mpg|ogg|pdf|png|ppt|pptx|qt|rar|rm|swf|tar|tgz|txt|wav|xls|xlsx|zip))$ {
    access_log off;
    expires 7d;
    add_header Cache-Control public;

 try_files $uri @fallback;
}

include "/var/www/vhosts/system/domain.es/conf/vhost_nginx.conf";
}

And some of the configuration vars I use with Apache (httpd.conf):

<IfModule prefork.c>
StartServers      14
MinSpareServers    8
MaxSpareServers   14
ServerLimit      1000
MaxClients       1000
MaxRequestsPerChild  2000
</IfModule>

Thank you very much in advance!