mysql> SELECT User,Host FROM mysql.user;

+-------+--------------+------------+
| User  | Host         | Grant_priv |
+-------+--------------+------------+
| root  | localhost    | Y          |
| root  | dev-db01     | Y          |
| root  | 127.0.0.1    | Y          |
| root  | ::1          | Y          |
|       | localhost    | N          |
|       | dev-db01     | N          |
| admin | %            | N          |
| admin | localhost    | N          |
| admin | xx.xxx.x.xxx | N          |
+-------+--------------+------------+

mysql> GRANT ALL PRIVILEGES ON *.* TO 'admin'@'xx.xxx.x.xxx' WITH GRANT OPTION;

mysql> GRANT ALL PRIVILEGES ON *.* TO 'admin'@'%' WITH GRANT OPTION;

mysql> GRANT ALL PRIVILEGES ON *.* TO 'admin'@'localhost' WITH GRANT OPTION;

mysql> FLUSH PRIVILEGES;

telnet xx.xxx.x.xx 3306

Trying xx.xxx.x.xx...
Connected to xx.xxx.x.xx.
Escape character is '^]'.
EHost 'xx.xxx.x.xx' is not allowed to connect to this MySQL serverConnection closed by foreign host.

sudo vi app/config/parameters.yml
parameters:
database_driver:   pdo_mysql
database_host:     xx.xxx.x.xx
database_port:     3306
database_name:     appdatabasename
database_user:     admin
database_password: ~

mysql> update db set Host='xx.xxx.x.xxx' where Db='placeholder_db';
mysql> update user set Host='xx.xxx.x.xxx' where user='placeholder_user';