Hardware issues: PoE power budget exceeded, wrong PoE standard, transceiver mismatch, signal strength

Some network problems come from the hardware itself: not enough power, incompatible modules or signals too weak to be understood. These issues often look like a device being dead, unstable or partly working, which tempts people to replace the device rather than find the cause. Knowing the patterns saves time and money, and the exam presents them as short scenarios with a telling detail, such as 'only some cameras power on' or 'the link works at one end but not the other'.