Edit or create a default vhost and put this inside:

<VirtualHost *:80> 

     ServerName xxx.xxx.xxx.xxx 
     403 /
DocumentRoot /var/www/html 
</VirtualHost>

xxx.xxx.xxx.xxx is your server ip address

After that restart your apache

sudo a2ensite your-vhost.conf 
sudo systemctl restart apache2

source: Stackoverflow