still suffering 404 after changing permalink settings

I’m using WP 4.1 version and I’m trying to change permalink settings from default to https://my_blog_addr/%post_id%.

WP is installed under /var/www/blog and I already enabled mod_rewrite by a2enmod command.
.htaccess file is located in /var/www/blog and also editable by WordPress(I confirmed that the file is created and several lines with # BEGIN WordPress are nicely added).

Here is my 000-default.conf file under /etc/apache2/sites-available below.

<VirtualHost *:80>
   ServerAdmin admin@localhost

   DocumentRoot /var/www
   <Directory />
     Options FollowSymLinks
     AllowOverride None
   </Directory>
   <Directory /var/www/>
     Options FollowSymLinks MultiViews
     AllowOverride FileInfo
     Order allow,deny
     allow from all
   </Directory>
   <Directory /var/www/blog>
     Options FollowSymLinks MultiViews
     AllowOverride All
     Order allow,deny
     allow from all
   </Directory>

   ScriptAlias /cgi-bin/ /usr/lib/cgi-bin/
   <Directory "/usr/lib/cgi-bin">
     AllowOverride None
     Options +ExecCGI -MultiViews +SymLinksIfOwnerMatch
     Order allow,deny
     Allow from all
   </Directory>

   ErrorLog ${APACHE_LOG_DIR}/error.log
   LogLevel warn

   CustomLog ${APACHE_LOG_DIR}/access.log combined
      Alias /doc/ "/usr/share/doc/"
     <Directory "/usr/share/doc/">
          Options Indexes MultiViews FollowSymLinks
          AllowOverride None
          Order deny,allow
          Deny from all
          Allow from 127.0.0.0/255.0.0.0 ::1/128
      </Directory>
  </VirtualHost>

I cannot understand why I’m still suffering 404 problem except main page. How can I fix this?