In order to avoid any possible import issues because of your server and php its settings, we would recommend setting up following PHP values in your server’s php.ini:
You can verify your PHP configuration limits by installing a simple plugin "Host PHP Info":
https://wordpress.org/plugins/host-php-info/
or by creating a phpinfo page. Follow the next steps to create a phpinfo page using your FTP File Manager:
<?php phpinfo();
If you don’t have an access to the php configurtation on your server, you can try to set this values in .htaccess file:
php_value max_input_vars 4000
php_value max_execution_time 180
php_value memory_limit 512M
php_upload_max_filesize 16M
Pls be careful, because some of hosting companies don’t allow to change php settings directly using .htaccess. In case you have some problems after modifying your .htaccess file, log in to your FTP account and remove these modifiactions from .htaccess
In any case you can contact your hoster and ask him to set required settings.