Zabbix agent is Unreachable for 5 mins

[sercan.gulsen]

Zabbix Agent gets “Zabbix agent is Unreachable for 5 mins” error. When we check in local, port 10050 is open and listening, when i check logs; logs are given below. I would like to ask for your support about this.

Zabbix Agent Logs
50968:20160923:165446.001 Starting Zabbix Agent [Windows host]. Zabbix 3.0.0 (revision 58455).
50968:20160923:165446.001 **** Enabled features ****
50968:20160923:165446.002 IPv6 support: YES
50968:20160923:165446.002 TLS support: NO
50968:20160923:165446.002 **************************
50968:20160923:165446.002 using configuration file: C:\zabbix\conf\zabbix_agentd.win.conf
50968:20160923:165446.010 agent #0 started [main process]
52208:20160923:165446.010 agent #1 started [collector]
50440:20160923:165446.044 agent #2 started[listener #1]
52888:20160923:165446.044 agent #3 started[listener #2]
51608:20160923:165446.045 agent #4 started[listener #3]

[guzzijason]

Blocked by access control? Did you check the Server config parameter in zabbix_agentd.conf to make sure your agent is allowing connections from the right host?

__Jason

[rthonpm]

Do you have any firewalls blocking IPv6 connections? I've seen a few instances of a monitored system trying to use IPv6 to communicate with the Zabbix server, which had its firewall set to only allow IPv4 connections.

[peterloron]

Also check your queue to make sure the checks are not backed up. That can cause issues.

[batchenr]

simple check -
telnet <ip of zabbix server> 10050 ---> at agent machine
telnet <ip of agent> 10050 ---> at zabbix server