wrong reason
The same IP produce too much (more than mysql database max_connection_errors maximum) error database connection in a short time and cause of obstruction.
When a client connection to the server timed out (more than connect_timeout), the server will give this record a client error, the error when the number reaches max_connect_errors time, the client will be locked. It is possible to try to set this value based on business bigger.
Solution
1. Increase of the number of allowed max_connect_errors
Run the following command (provisional entry into force, after the restart failure)
set global max_connect_errors=500;
Or add the following configuration in mysql configuration file (permanent)
max_connect_errors=500
2. Use clear the cache, which would clean out the count
Into the mysql console, do the flush hosts
mysql>flush hosts;
Mysql installation directory or to the use mysqladmin -u root -p flush-hosts command, enter a password, complete clearing cache
Reference address