An error appears in the log when monitoring DB port

[carloooos]

Zabbix Server 3.0.22 (CentOS7.5)
DB : MySQL 5.6.40

I am monitoring the DB(MySQL 5.7.12) port at Zabbix Server.
However, the following error is output to the monitoring target DB, and I am in trouble.

Steps to reproduce:

1. Register the host of the target DB.
2. Set the item key using 「net.tcp.service」or 「net.tcp.port」.

Result:
The following errors are output at the item acquisition interval in the error log of the monitoring target database.

2019-03-14T04:37:23.750629Z 10196 [Note] Aborted connection 10196 to db: 'unconnected' user: 'unauthenticated' host: '10.51.43.31' (Got an error reading communication packets)

10.51.43.31：Zabbix Server IP

[Ron806]

Open the port specified during installation and restart the agent. If necessary you can monitor outside the firewall using an SSH tunnel tellthebell.