During a storm, PoE devices on three Dell N3048 switches lost power, while the switches and non-PoE connections stayed up. Cycling PoE on the affected ports brought the devices back. Some devices are outdoors, and the switches are on UPS power.
What could cause that, and what should I check before explaining it to management?
A plausible explanation is a transient induced in a network cable by a nearby strike. It wouldn't need to be a direct hit on a device. A voltage spike or other disturbance on a cable could cause the PoE circuitry to shut down power, while the switch itself keeps forwarding traffic.
That's a theory, not a diagnosis. The port reset restoring power is consistent with a latched fault or disrupted PoE detection, but it doesn't prove either happened. Check the switch logs and PoE fault status around the time of the storm before calling it a protection trip.
Next time, grab the PoE status before cycling the ports if you can. Look for fault, detection, class, and power consumption information, plus any switch and UPS events at the same timestamp. Save the logs because a reset may clear useful clues.
A port showing link down while still reporting a power class is worth recording, but it doesn't establish what the PoE controller was doing. Check the N3048 documentation for what those fields mean on that firmware.
I'd look closely at the outdoor runs and where cables enter the building. Have someone qualified check grounding and bonding, cable routes, and whether suitable surge protection is installed at the entry points. An electrical disturbance could also arrive through the power system, so don't assume the outdoor cables were definitely the path.
Shielded cable alone isn't a lightning fix. Its grounding and installation matter, and a sufficiently strong surge can still damage equipment.
For management, keep the explanation tentative: the outage coincided with the storm, affected PoE rather than general switch operation, and cleared after port power was cycled. Lightning-related interference is a credible possibility, but the available evidence doesn't identify the exact path or fault.
Keep an eye on the affected ports and devices for recurring faults. Recovery is good news, but it doesn't by itself prove whether anything was damaged.
Answers are reviewed before publication.
-please-use-other-side:
The UPS doesn't rule out a cable-side transient. It protects the switch's power feed, not every Ethernet run connected to it.