If your Cisco switch PoE is not working, the most common causes are an exhausted PoE power budget, a disabled inline power configuration, physical cable faults, incompatible powered devices (PD), or a crashed PoE controller. Power over Ethernet (PoE) technology plays a vital role in modern network infrastructure by simplifying device deployment — delivering both power and data over a single Ethernet cable. To isolate the problem fast, log into the Catalyst switch and run show. I encountered an anomalous error on the Cisco C1300-24FP-4X switch. [16:48:34]20-Feb-2025 21:45:06 :%HAL_config_poe-C-poePowerHWFail: POE ERROR (MCU fault) was detected. When a problem occurs with PoE, in most cases, the error symptom can be simply shown as the PoE switch not providing power, and the powered devices will stop. Your UniFi switch is up, your devices are plugged in, and everything looks good, until you realize your access point or camera isn't powering on. If you're staring at a dead UniFi device connected to a PoE port, this guide is for you.