In the httpd-mpm.conf file you find a section with

mpm_winnt_module

ThreadsPerChild defines the max number of concurrent connections. Default 150.0 Sure you can increase that.

For mariadb see https://mariadb.com/kb/en/server-system-variables/#max_connections

Tuning: - Disable mod_status. That will increase the speed a lot. - Use PHP not as a module but use mod_fcgid. - Disable the use of .htaccess (AllowOverride)

When you have hangs, slow traffic and/or when having in your log entries like Asynchronous AcceptEx failed. You can try the following settings:

AcceptFilter http none AcceptFilter https none EnableSendfile off EnableMMAP off