Zabbix Agent working intermittently

[cyberphantom]

I have 4 hosts being monitored by a Zabbix Proxy. I installed the Zabbix Agent on these 4 hosts, all of which are running Red Hat 7.9. The agents are working, but for 2 of the hosts, the Zabbix Agent Availability is intermittent. Sometimes it is OK, but sometimes it stops. I noticed that the Zabbix Agent ping has multiple gaps in the graphs, even though the normal ICMP ping is consistently OK. When the agent stops, I see the message on the host: "Get value from agent failed: ZBX_TCP_READ() timed out". I searched the agent logs but found nothing.
I've searched for a firewall, but there isn't one on either host. I already tried running "tcpdump -i interface port 10051" to capture the communication while the Zabbix Agent was stopped, but there was absolutely nothing relevant, nothing related to the error. What do you recommend me to check?

I've attached my zabbix agentd file config

[Markku]

Actually the traffic capture should clearly indicate if the TCP connection had problems. 10051 is the port used by active agents, so is your agent.ping items active? For passive items correct port is 10050.

Markku