UniFi Switch Has No Power, Briefly Flashes or Does Not Power a PoE Device

First distinguish between a switch that will not stay powered and a working switch whose connected AP, camera or other PoE device has no power. A brief flash alone does not identify the failed component.

1. Confirm the switch's power input

Find the exact model and check its official technical specifications and installation guide. UniFi switches use different inputs: mains AC, an external DC adapter, USB-C or PoE input, depending on the model. A switch with PoE outputs does not necessarily accept PoE as its own power source.

For an adapter-powered model, use the specified supply and check its label and connection. Do not substitute a supply solely because its plug fits. If there is visible damage, liquid exposure, smoke or a burning smell, disconnect power safely and request assistance.

2. Check the power path

1. Check that the supply, power cord and outlet are securely connected and available. Inspect the external cable and adapter without opening the equipment.
2. Check the model's LED/LCD guidance. Some switch displays remain dark briefly after an update; do not disconnect power during an update.
3. Where a service interruption is acceptable, isolate the attached devices and test with the correct supply. Record whether the switch stays on without its downstream load. Avoid repeated cycling of a unit that immediately shuts down.

3. If only a connected device lacks PoE

• Confirm that the chosen port provides PoE and is enabled, and that its PoE type meets the device's requirement.
• Check both the per-port limit and the switch's remaining total PoE budget. The available budget can depend on how some compact switches are powered.
• Try a known-good cable and a correctly rated alternate port or approved adapter, changing one item at a time. Do not connect a passive PoE output to an ordinary data-only device.

Send our Specialist the model, power-supply label, LED behaviour, connected-device list, PoE usage and test results. A warranty assessment follows the purchase evidence and fault checks.