Varnish重定向问题：独立服务器上Magento实例的Nginx虚拟主机配置咨询

我最近碰到了Varnish重定向的相关问题，先把我在独立服务器上为Magento实例配置的Nginx主配置文件内容贴出来，想请大家帮忙看看哪里可能出了问题：

user  www-data;
worker_processes  auto;
worker_rlimit_nofile 50000;

error_log  /var/log/nginx/error.log notice;
pid        /var/run/nginx.pid;


events {
    worker_connections  20000;
    multi_accept        on;
    use                 epoll;
}

http {

    ##
    # Basic Settings
    ##

    autoindex       off;
    sendfile on;
    tcp_nopush on;
    tcp_nodelay on;
    keepalive_timeout 25;
    client_body_timeout 15;
    client_header_timeout 15;
    send_timeout 15;
    types_hash_max_size 2048;
    server_tokens off;
    client_max_body_size 64M;
    client_body_buffer_size 128k;
    client_header_buffer_size 16k;
    large_client_header_buffers 4 16k;
    fastcgi_read_timeout 300;
#    proxy_read_timeout 300;
    fastcgi_buffer_size 32k;
    fastcgi_buffers 16 32k;
    # server_names_hash_bucket_size 64;
    # server_name_in_redirect off;

    include       /...
}

备注：内容来源于stack exchange，提问作者G. G.