We're using Zabbix 4.0 LTS with active Zabbix Agent checks and PSK encryption successfully with over 200 hosts.

But now we have a strange problem with two new hosts: the checks cannot be retrieved from the server by the agent. The configuration is 100% identical with all the other hosts.

Error in Zabbix Agent log:

active check configuration update from [monitoring.example.com:10051] started to fail (SSL_read() timed out)

Log from the server contains no information. Increased debug level at the agent does not result in anything interesting either.

It works only with encryption disabled.

Zabbix Server version: 4.0.17

Zabbix Agent versions tried: 4.0.10, 4.0.16, 4.4.5

OS: Windows 10