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. This guide is for troubleshooting Power over Ethernet (PoE) in the Catalyst 3750-E, 3750, 3560-E, and 3560 switch product families. Topics related to earlier PoE switches are also included. For precise CLI and message format, see the switch software configuration guides and command references for. Despite its convenience, PoE can sometimes fail or behave unpredictably, causing devices to lose power, intermittently disconnect, or fail to start. Firmware Errors – Check on the device if there are any.