php-fpm process: SQLSTATE[HY000] [2002] Connection timed out with database

Description

I have a problem with upgrading a server from Centos to Ubuntu (both use Nginx, php, mysql, laravel application)

OS version:

• Centos: CentOS Linux release 7.9.2009 (Core)
• Ubuntu: Ubuntu 22.04.4 LTS

Nginx version:

• Centos: nginx/1.20.1
• Ubuntu: nginx/1.18.0 (Ubuntu)

PHP version:

• Centos: PHP 8.1.29 (cli)
• Ubuntu: PHP 8.1.29 (cli)

mysql connection is the same for both servers

php-fpm config is the same for both servers, command check php-fpm8.1 -tt

pm = dynamic
pm.max_children = 500
pm.start_servers = 50
pm.min_spare_servers = 50
pm.max_spare_servers = 350
pm.max_spawn_rate = 32
pm.process_idle_timeout = 10
pm.max_requests = 0

When the number of requests is large, the Centos server will operate normally, but the Ubuntu server will have some requests with connection timeout errors as follows:

SQLSTATE[HY000] [2002] Connection timed out {"exception":"[object] (PDOException(code: 2002): SQLSTATE[HY000] [2002] Connection timed out at /vendor/laravel/framework/src/Illuminate/Database /Connectors/Connector.php:70)

Could you please share more knowledge about this issue?

Thank you 🙇

PHP Version

PHP 8.1.29

Operating System

Ubuntu 22.04.4 LTS