The installer says: Your server meets all of XenForo requirements and you're now ready to begin installation. Knowing that the MySQL port for 1&1 is: /tmp/mysql5.sock I put it, but the installer tells me: The following error occurred while connecting to the database: Access denied for user: 'dboXXX@localhost' (Using password: YES) This indicates that your configuration information is not correct. Please check the values you have entered. If you are unsure what values are correct or how to proceed, please contact your host for help. These values are specific to your server. I edited the config.php manually: $config['db']['host'] = 'localhost'; $config['db']['port'] = '/tmp/mysql5.sock'; $config['db']['username'] = 'dboXX'; $config['db']['password'] = 'XXX'; $config['db']['dbname'] = 'dbXXX'; This configuration works well with vBulletin 4: $config['Database']['dbname'] = 'dbXXX'; $config['MasterServer']['servername'] = 'localhost'; $config['MasterServer']['port'] = '/tmp/mysql5.sock'; $config['MasterServer']['username'] = 'dboXXX'; $config['MasterServer']['password'] = 'XXX'; But still not working Nevertheless, I added php_value mysql.default_socket "/tmp/mysql5.sock" to .htaccess, as shown here (although is not necessary for vBulletin 4): http://www.vbulletin.com/forum/showthread.php?301047-Database-connection-error/page2 But still not working, so you have to communicate because it is almost certain that the problem is in the interpretation of the port. Please do you can fix so we can test the beta?