App is very slow when I connect my external IP in home network

Nextcloud mobile app is very slow when i connect by my external IP in my home network. (some times it occurs time out error!) if I change wifi to LTE, app works very fast. but, definitely, LTE network in my home is 1/100 speed of my wifi.

And same divice in wifi network, although app is very slow, but nextcloud web is fast enough.

Using my Internal IP, both web and app is fast.

Why app is slow when I connect by external IP??

Belwo is my configuration file of apache2 and nextcloud.

<VirtualHost *:80>
# The ServerName directive sets the request scheme, hostname and port that
# the server uses to identify itself. This is used when creating
# redirection URLs. In the context of virtual hosts, the ServerName
# specifies what hostname must appear in the request’s Host: header to
# match this virtual host. For the default virtual host (this file) this
# value is not decisive as it is used as a last resort host regardless.
# However, you must set it for any further virtual host explicitly.

    ServerAdmin webmaster@localhost
    DocumentRoot /var/www/nas

    # Available loglevels: trace8, ..., trace1, debug, info, notice, warn,
    # error, crit, alert, emerg.
    # It is also possible to configure the loglevel for particular
    # modules, e.g.
    #LogLevel info ssl:warn

    ErrorLog ${APACHE_LOG_DIR}/error.log
    CustomLog ${APACHE_LOG_DIR}/access.log combined

    # For most configuration files from conf-available/, which are
    # enabled or disabled at a global level, it is possible to
    # include a line for only one particular virtual host. For example the
    # following line enables the CGI configuration for this host only
    # after it has been globally disabled with "a2disconf".
    Alias /webdav /media/nas/hdd1/home
    <Location /webdav>
            DAV On
            AuthType Basic
            AuthName "Login with your information."
            AuthUserFile /etc/apache2/webdav.pwd
            Require valid-user
    <Directory /media/nas/hdd1/home>
            Options Indexes FollowSymLinks MultiViews
            AllowOverride None
            Order allow,deny
            allow from all

    Alias /nextcloud /var/www/nextcloud/
    <Directory /var/www/nextcloud/>
            Options +FollowSymlinks
            AllowOverride All
    <IfModule mod_dav.c>
            Dav off
    SetEnv HOME /var/www/nextcloud
    SetEnv HTTP_HOME /var/www/nextcloud

vim: syntax=apache ts=4 sw=4 sts=4 sr noet

$CONFIG = array (
  'passwordsalt' => 'rF/kxFmFWB0+wtGQ5oof/C8s2vryDa',
  'secret' => 'gRQidVzE6ltKzGERoQHcA1CLCZRKQEwOr0N3J0U47GccPP6F',
  'trusted_domains' =>
  array (
    0 => 'localhost',
    1 => '',
    2 => '',
  'memcache.local' => '\\OC\\Memcache\\APCu',
  'datadirectory' => '/media/nas/hdd1/nextcloud-data',
  'overwrite.cli.url' => 'http://localhost',
  'dbtype' => 'mysql',
  'version' => '',
  'dbname' => 'nextcloud-db',
  'dbhost' => 'localhost',
  'dbport' => '',
  'dbtableprefix' => 'oc_',
  'dbuser' => 'nextcloud',
  'dbpassword' => 'mypassword',
  'installed' => true,
  'instanceid' => 'occk2blch6h2',
  'updater.secret' => '$2y$10$6EnN6evp3WVVkGLkcR8BkuMjys3xEaAcLmC52KgytRQeFNxeyyCl6',
  'maintenance' => false,
  'theme' => '',
  'loglevel' => 2,

I tried change my server to nginx, and changed port of nextcloud but not a solution. same problem occur.

and I dissited other site of apache2, but, no effect… (App very slow when Nextcloud server is in same subnet)

How can I repair my nextcloud app?? Thank you…

I can’t know what is the cause, but this solved…

I just think cache of my router or app occured this problem.