I use nginx's(nginx1.10.2) ngx_http_limit_conn_module module to limit the number of concurrent connections. It works for HTTP requests, but it doesn't work for HTTPS.nginx config as follows

limit_conn_zone $server_name zone=one:10m;
server {
    listen       80;
    listen       443 ssl;
    server_name  test-esign.mbcloud.com;
    #ssl on;
    ssl_certificate "/etc/nginx/conf.d/crtdomain/server.cer";
    ssl_certificate_key "/etc/nginx/conf.d/crtdomain/server.key";
    ssl_session_cache shared:SSL:1m;
    ssl_session_timeout  10m;
    ssl_ciphers HIGH:!aNULL:!MD5;

    location / {
        limit_conn one 1;
        root   /usr/share/nginx/html;
        index  index.html index.htm;
    }
}