E3-1240 with 32GB Ram - Unable to set the optimal value for the server

[agriz]

worker_processes  4;
worker_rlimit_nofile 40000;

events {
    worker_connections 4096;
#    accept_mutex on;
#    accept_mutex_delay 500ms;
    multi_accept on;
    use epoll;
}

pm.max_children = 50
pm.start_servers = 4
pm.min_spare_servers = 4
pm.max_spare_servers = 32
pm.max_requests = 2500 //modified
rlimit_files = 131072 //modified
rlimit_core = unlimited //modified

# TCP Stack changes 
net.ipv4.tcp_fin_timeout = 20 
net.ipv4.tcp_tw_reuse = 1
net.core.netdev_max_backlog = 10000 
net.core.somaxconn = 2048
net.ipv4.tcp_max_syn_backlog = 2048 
net.ipv4.ip_local_port_range = 15000 65000 

But still not efficient.
Losing visitors abnormally

Posted at Nginx Forum: https://forum.nginx.org/read.php?2,276892,276900#msg-276900