Why is 504 Gateway Timeout happening?

Question

HTML

Trying to set up dklab realplexor
This item:

Proxy calls to the Realplexor through nginx (if you don't have nginx, choose step 1):
server {
server_name rpl.YourSite.com;
listen rpl.YourSite.com:80;
location / {
proxy_pass http://127.0.0.1:8088;
}
}

/etc/nginx/vhosts/MYDOMAIN/dev.MYDOMAIN.com.conf

#user 'MYDOMAIN' virtual host 'dev.MYDOMAIN.com' configuration file
server {
  server_name dev.MYDOMAIN.com www.dev.MYDOMAIN.com;
  charset off;
  disable_symlinks if_not_owner from=$root_path;
  index index.html index.php;
  root $root_path;
  set $root_path /var/www/MYDOMAIN/data/www/dev.MYDOMAIN.com;
  ssi on;
  access_log /var/www/httpd-logs/dev.MYDOMAIN.com.access.log ;
  error_log /var/www/httpd-logs/dev.MYDOMAIN.com.error.log notice;
  listen dev.MYDOMAIN.com:80;
  include /etc/nginx/vhosts-includes/*.conf;
  location / {
    location ~ [^/]\.ph(p\d*|tml)$ {
      try_files /does_not_exists @fallback;
    }
    location ~* ^.+\.(jpg|jpeg|gif|png|svg|js|css|mp3|ogg|mpe?g|avi|zip|gz|bz2?|rar|swf)$ {
      try_files $uri $uri/ @fallback;
    }
    location / {
      try_files /does_not_exists @fallback;
    }
  }
  location @fallback {
    error_log /dev/null crit;
    proxy_pass http://127.0.0.1:8088;
    proxy_redirect http://127.0.0.1:8088 /;
    proxy_set_header Host $host;
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_set_header X-Forwarded-Proto $scheme;
    access_log off ;
  }
}

When going to dev.MYDOMAIN.com, an error occurs: 504 Gateway Time-out. Why is that?
Initial config /etc/nginx/vhosts/MYDOMAIN/dev.MYDOMAIN.com.conf:

#user 'MYDOMAIN' virtual host 'dev.MYDOMAIN.com' configuration file
server {
  server_name dev.MYDOMAIN.com www.dev.MYDOMAIN.com;
  charset off;
  disable_symlinks if_not_owner from=$root_path;
  index index.html index.php;
  root $root_path;
  set $root_path /var/www/MYDOMAIN/data/www/dev.MYDOMAIN.com;
  ssi on;
  access_log /var/www/httpd-logs/dev.MYDOMAIN.com.access.log ;
  error_log /var/www/httpd-logs/dev.MYDOMAIN.com.error.log notice;
  listen IP_ADDRESS:80;
  include /etc/nginx/vhosts-includes/*.conf;
  location / {
    location ~ [^/]\.ph(p\d*|tml)$ {
      try_files /does_not_exists @fallback;
    }
    location ~* ^.+\.(jpg|jpeg|gif|png|svg|js|css|mp3|ogg|mpe?g|avi|zip|gz|bz2?|rar|swf)$ {
      try_files $uri $uri/ @fallback;
    }
    location / {
      try_files /does_not_exists @fallback;
    }
  }
  location @fallback {
    error_log /dev/null crit;
    proxy_pass http://127.0.0.1:8080;
    proxy_redirect http://127.0.0.1:8080 /;
    proxy_set_header Host $host;
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_set_header X-Forwarded-Proto $scheme;
    access_log off ;
  }
}

/etc/dklab_realplexor.conf

$CONFIG{WAIT_ADDR} = [ '127.0.0.1:8088' ]; # your IP address and port
$CONFIG{IN_ADDR} = [ '127.0.0.1:10010' ]; # for IN line

/var/log/messages

May 16 19:14:48 domain realplexor/dklab_realplexor.conf: [Sat May 16 19:14:48 2015] WAIT: 127.0.0.1:42387: DEBUG: [1431792828.85733000600000:domain_Alpha] connection closed
May 16 19:14:48 domain realplexor/dklab_realplexor.conf:   [pairs_by_fhs=0 data_to_send=0 connected_fhs=0 online_timers=1 cleanup_timers=0 events=1]
May 16 19:14:49 domain realplexor/dklab_realplexor.conf: [Sat May 16 19:14:49 2015] WAIT: 127.0.0.1:46225: DEBUG: connection opened
May 16 19:14:49 domain realplexor/dklab_realplexor.conf:   [pairs_by_fhs=0 data_to_send=0 connected_fhs=0 online_timers=1 cleanup_timers=0 events=1]
May 16 19:14:49 domain realplexor/dklab_realplexor.conf: [Sat May 16 19:14:49 2015] WAIT: 127.0.0.1:46225: DEBUG: read 544 bytes
May 16 19:14:49 domain realplexor/dklab_realplexor.conf:   [pairs_by_fhs=0 data_to_send=0 connected_fhs=0 online_timers=1 cleanup_timers=0 events=1]
May 16 19:14:49 domain realplexor/dklab_realplexor.conf: [Sat May 16 19:14:49 2015] WAIT: 127.0.0.1:46225: DEBUG: [1431792889.23384000800000:domain_Alpha] registered
May 16 19:14:49 domain realplexor/dklab_realplexor.conf:   [pairs_by_fhs=1 data_to_send=0 connected_fhs=1 online_timers=1 cleanup_timers=0 events=1]
May 16 19:15:41 domain realplexor/dklab_realplexor.conf: [Sat May 16 19:15:41 2015] WAIT: 127.0.0.1:49078: DEBUG: connection opened
May 16 19:15:41 domain realplexor/dklab_realplexor.conf:   [pairs_by_fhs=1 data_to_send=0 connected_fhs=1 online_timers=1 cleanup_timers=0 events=1]
May 16 19:15:41 domain realplexor/dklab_realplexor.conf: [Sat May 16 19:15:41 2015] WAIT: 127.0.0.1:49078: DEBUG: read 437 bytes
May 16 19:15:41 domain realplexor/dklab_realplexor.conf:   [pairs_by_fhs=1 data_to_send=0 connected_fhs=1 online_timers=1 cleanup_timers=0 events=1]
May 16 19:15:41 domain realplexor/dklab_realplexor.conf: [Sat May 16 19:15:41 2015] WAIT: 127.0.0.1:46225: DEBUG: [1431792889.23384000800000:domain_Alpha] connection closed
May 16 19:15:41 domain realplexor/dklab_realplexor.conf:   [pairs_by_fhs=0 data_to_send=0 connected_fhs=0 online_timers=1 cleanup_timers=0 events=1]
May 16 19:15:41 domain realplexor/dklab_realplexor.conf: [Sat May 16 19:15:41 2015] WAIT: 127.0.0.1:49110: DEBUG: connection opened
May 16 19:15:41 domain realplexor/dklab_realplexor.conf:   [pairs_by_fhs=0 data_to_send=0 connected_fhs=0 online_timers=1 cleanup_timers=0 events=1]
May 16 19:15:41 domain realplexor/dklab_realplexor.conf: [Sat May 16 19:15:41 2015] WAIT: 127.0.0.1:49110: DEBUG: read 544 bytes
May 16 19:15:41 domain realplexor/dklab_realplexor.conf:   [pairs_by_fhs=0 data_to_send=0 connected_fhs=0 online_timers=1 cleanup_timers=0 events=1]
May 16 19:15:41 domain realplexor/dklab_realplexor.conf: [Sat May 16 19:15:41 2015] WAIT: 127.0.0.1:49110: DEBUG: [1431792941.33419000900000:domain_Alpha] registered
May 16 19:15:41 domain realplexor/dklab_realplexor.conf:   [pairs_by_fhs=1 data_to_send=0 connected_fhs=1 online_timers=1 cleanup_timers=0 events=1]
May 16 19:15:46 domain realplexor/dklab_realplexor.conf: [Sat May 16 19:15:46 2015] WAIT: 127.0.0.1:49110: DEBUG: [1431792941.33419000900000:domain_Alpha] connection closed
May 16 19:15:46 domain realplexor/dklab_realplexor.conf:   [pairs_by_fhs=0 data_to_send=0 connected_fhs=0 online_timers=1 cleanup_timers=0 events=1]

Answer 1

I understand that this is input type="range"
But how to draw such a conclusion?

Let's go from the opposite.
Is this a gallery? No
Is this a hidden input? No
...
Is it input type=range? Yes
Maybe look in a math textbook? No
Ask the salesperson in the store? No
...
Drive it into the search or look in the sandbox? Yes
search 1
search 2
sandbox

Answer 2

I understand that this is input type="range"

No, these are normal divs or spans and 2 inputs to them, processed by js
ionden.com/a/plugins/ion.rangeSlider
Standard range is 1 slider.

Answer 3

Check that realplexor is running and really listening on port 8088.