Import from Joomla to WP error

Hi,

I'm trying to import an old Joomla website (1.5.28) to the latest version of WP with FG Joomla to Wordpress plugin.
But i get an error when testing the connection to MySQL server:
Warning: PDO::__construct(): php_network_getaddresses: getaddrinfo failed: Name or service not known in /wp-content/plugins/fg-joomla-to-wordpress/admin/class-fg-joomla-to-wordpress-admin.php on line 342
Import Joomla (FG)

[fgj2wp] Impossible de se connecter à la base de données de Joomla. Merci de vérifier vos paramètres. Et soyez certains que le serveur WordPress ait accès à la base de données de Joomla.
SQLSTATE[HY000] [2002] php_network_getaddresses: getaddrinfo failed: Name or service not known

I tested a second plugin and i get the same error, so it's probably not linked to the plugin but to something else that i can not determine.
Could you please help ?

Thank you in advance
Chris