请求超时 - 500内部服务器错误

Question

I am working in cakephp3.0. And one of my function needs more time to run. When I run that function it shows "500 internal error","This request takes too long to process, it is timed out by the server. If it should not be timed out, please contact administrator of this web site to increase 'Connection Timeout'." php ini file is

    allow_url_fopen = On
    allow_url_include = On
    asp_tags = Off
    display_errors = Off
    enable_dl = On
    file_uploads = On
    max_execution_time = 900
    max_input_time = -1
    max_input_vars = 100000;
    memory_limit = 128M
    post_max_size = 700M
    session.gc_maxlifetime = 43200
    session.save_path = "/tmp"
    upload_max_filesize = 999M;
     zlib.output_compression = On

and htaccess file is

    <IfModule mod_rewrite.c>
       RewriteEngine on
         RewriteBase /
         RewriteRule    ^$    webroot/    [L]
         RewriteRule    (.*) webroot/$1    [L]
     </IfModule>

     <IfModule php5_module>
       php_flag asp_tags Off
       php_flag display_errors Off
       php_value max_execution_time 900
       php_value max_input_time -1
       php_value max_input_vars 1000
       php_value memory_limit 128M
       php_value post_max_size 700M
       php_value session.gc_maxlifetime 43200
       php_value session.save_path "/tmp"
       php_value upload_max_filesize 250M
       php_flag zlib.output_compression On
  </IfModule>

We contacted server people and they told thay have increased the maximum execution time to 900. But still now it shows 500 page after 2 minutes. And now server people asking to fix the issue from development side.

I have gone through so many questions in stackoverflow. But I dont get a solution.

Thanks in advance