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. To isolate the problem fast, log into the Catalyst switch and run show. 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. However, when PoE fails, it can disable critical infrastructure like IP phones, wireless access points, and security cameras. PoE errors on the device seen on CLI.