The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received

在连接数据库的时候，报错以下：

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.

上网查，通常是设置超时时间，我这边设置超时时间是无论用的，敢确定的是没有设置mysql白名单或者网络不通的问题。