Connection failed: Host '172.31.4.7' is not allowed to connect to this MySQL server code example

Example 1: host is not allowed to connect to this mysql server

CREATE USER 'username'@'localhost' IDENTIFIED BY 'password';

GRANT ALL PRIVILEGES ON *.* TO 'username'@'localhost' WITH GRANT OPTION;

CREATE USER 'username'@'%' IDENTIFIED BY 'password';

GRANT ALL PRIVILEGES ON *.* TO 'username'@'%' WITH GRANT OPTION;

FLUSH PRIVILEGES;

Example 2: host not allowed to connect to this mysql server

mysql -u root -p
    -- root password

    CREATE USER 'username'@'localhost' IDENTIFIED BY 'password';

    GRANT ALL PRIVILEGES ON *.* TO 'username'@'localhost' WITH GRANT OPTION;

    CREATE USER 'username'@'%' IDENTIFIED BY 'password';

    GRANT ALL PRIVILEGES ON *.* TO 'username'@'%' WITH GRANT OPTION;

    FLUSH PRIVILEGES;

    EXIT;