504 Gateway Timeout

i have 2 Apache servers and 2 Loadbalance servers and one File server(centos 7)and i am using maria db cluster. i want to download som file from students i face a problem with this error: 504 Gateway Time-out The server didn't respond in time. i didn't find timeout in Httpd.conf. i have changed my php.ini : max_execution_time = 1330000 And in my Loadbalancer the set up for haproxy.cfg is: contimeout 5000 clitimeout 50000 srvtimeout 50000 Many Thanks for your help