Why my site is blocked by too many connection errors?
MySQL blocks clients which error made while connecting to protect MySQL from malformed client.

So first, you need to find what sort of error it is.

In example by checking MySQL error log in data directory (typically hostname.err) or if you've drush installed, by drush watchdog-show.

You may also increase max_connect_errors (what is current value?) maximum value depends on architecture (check Manual).

But this is not real solution if error is frequently occurred.

FLUSH HOSTS can help you to eliminate blocked host. E.g.

mysql&gt; FLUSH HOSTS;


Source: Why MySQL connection is blocked of many connection errors?

Please note that to use mysqladmin properly, you need to have access to root account. If you don't have it, use FLUSH HOSTS command as above.