How to fix 502 error with a large flow of users?

Question

Nginx

Good afternoon.
I have a site running on php-fpm+nginx+node with a stream of 400 people, nginx gives an error 502, how to fix it? Or what needs to be increased, what configs or where can I read?

Answer 1

helped

/etc/php5/fpm/pool.d/www.conf

pm.max_requests = *