Why does the server not allow connecting to the site in multiple threads?

Question

PHP

Hi ALL!
Given:
- Centos7
- apache-24-worker
- php55-fcgi
- MariaDB A
friend contacted me - he has a website on a self-written engine. When he enters the admin panel of his site and puts a file on download - for some incomprehensible reason, while the site is downloading from the site, the site does not open, we open 5 windows with the address of his site - everyone is waiting, as soon as the download is interrupted or it ends - in all in the windows, the site loaded instantly. If the download goes over a slow channel, Apache cuts the connection timeout and a 5xx error goes into the logs. Where to dig and what can be?

Answer 1

If the file is given by means, uzhos, php, then the session may be blocked. Try opening tabs in Incognito mode so that there is a new session - if they work without delay, then this is it

Answer 2

For example, some module may be included that implements a limit on the number of connections from one address.
For apache- stackoverflow.com/questions/450606/limit-number-of...
For nginx - nginx.org/ru/docs/http/ngx_http_limit_conn_module....
Maybe even using iptables

Answer 3

1) the limit on the number of connections from one ip is usually set somewhere either in iptables or in apache, there are many options for setting this limit
2) the execution time limit is set either in apache or most likely in php.ini, it is enough to increase max_execution_time

Answer 4

The programmer showed up - I'm waiting for his verdict.