I get error "Failed to connect to your database server. The server reports the following message: SQLSTATE[HY000]  Can't connect to MySQL server on '192.168.0.20' (13)." while installing drupal.
credentials are correct.
on webserver: mysql -u dbuser -h 192.168.0.20 -P 3306 -D drupal -p works fine.
what could be problem ?