Zabbix agent on <host> unreachable issue

[vicchern]

Hello guys.
We are faced with an issue with Zabbix 5.0.15.
We are working with AWS servers.
Zabbix_agentd version is v2.4.7.

Few days ago started appearing and issue

Zabbix agent on <host> unreachable

on each of 30 servers. For notifications, we are using PagerDuty. It becomes crazy to follow.

agent.ping

shows that everything is OK. ZBX icons on the front end are green.
The first and second times the issue was healed by

sudo service zabbix-server restart

I was thinking about the ServerActive value in the zabbix_agentd.conf file. It was 127.0.0.0. I changed it to the IP address of the server. The issue didn't disappear.
The problem is not permanent. After restart, it disappears and appears again after a few days.

Please, guys, maybe you have any suggestions?