How a firmware bug caused an intermittent network outage in my home lab

In this article, the author shares the story of troubleshooting a perplexing network issue that disrupted daily work despite a high-end network setup. The issue involved intermittent connectivity drops on a Mac Mini, which appeared to be a local network problem, but the investigation revealed that the problem was not related to software or hardware directly. After many theories were explored—such as software bugs, hardware issues, and network protocols—the author discovered that the root cause was ARP poisoning triggered by a bug in a managed switch. The switch was incorrectly responding to ARP requests for the gateway’s IP, causing the Mac to lose its connection. The article concludes with insights on troubleshooting complex network problems and emphasizes the importance of verifying all components, even seemingly minor devices, like cheap switches.