We are using Checkmk 2.4.0p35 and have a Windows host showing the warning “TLS is not activated on monitored host”. To enable TLS, we attempted to register the existing agent using cmk-agent-ctl, but the registration fails with the error “unexpected EOF during handshake” while connecting to the /agent-receiver/register_existing endpoint. The host is already monitored successfully and agent data is being collected without any issues. We would like to understand whether this error is related to a port configuration issue (such as port 8000 used by the Agent Receiver), a firewall or network restriction, or a server-side TLS configuration problem.
Has anyone experienced a similar issue with Checkmk 2.4.0p35, and what logs or troubleshooting steps would you recommend to identify the root cause? Any suggestions would be greatly appreciated. Refer to the snippets attached below.