# Zabbix Proxy not communicating with Windows Server `Interrupted system call` - I've seen these in zabbix when connections are timed out. tcpdump is your best friend in this case. On the agent host, `tcpdump -i any -n tcp port 10050` and see if you get incoming packets, if not, then there is something between the boxes or you don't have proper routing between the boxes or the host configuration in server has wrong IP. If instead you see incoming packets but not outgoing, then you do have a local firewall (iptables). Finally, if you see both incoming and outgoing, then you have to check on the server side if the response from agent gets there. If it does, then, finally, it is a strange situation. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.arkannis.net/monitoring/zabbix/zabbix-proxy-not-communicating-with-windows-server.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.