That port was never a PoE port
very common
“Moved the camera four ports over and it fired straight up. Same cable, same camera. The one it was on just does nothing at all.”
Likely causes
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Only some ports on the switch are PoE, or only some do PoE+ or bt
35%Every working PoE device on that switch sits inside the same numeric range. The switch's own port capability output shows the dead port as non-PoE, or as a lower Type than the PD needs. Cheap access switches and mixed chassis are where this lives.
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PoE daughtercard, expansion module or line card absent, failed or not seated
20%A whole block of ports has no PoE capability while another block works normally. The chassis inventory shows the module missing, failed, or sitting in a slot that does not support it.
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PoE behind a feature licence that was never applied
15%The hardware supports PoE and the CLI reports it unlicensed, unavailable or expired. The licence page shows it unassigned. Nothing about the port config is wrong.
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PoE disabled globally by a power-management policy or a provisioning template
15%No port on the switch delivers power, including ports that certainly should. Global inline power is off, or a policy applied at provisioning turned it off and nobody has looked at it since.
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PD patched into an uplink, combo or SFP-adjacent port
10%The link comes up perfectly and the port will never power anything. Trace the patch rather than trusting the label on the panel.
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Different switch on the wall than the one in the as-builts
5%The model on the label does not match the design. A non-PoE or lower-budget SKU went in during a previous repair and the drawings were never updated.
What to bring
- Switch CLI for port capability and chassis inventory
- Switch datasheet port map for the exact SKU
- Licence status page or vendor portal
- Patch panel records and as-builts
- Known-good PD
Steps
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Step 1: Read the switch's own port capability output before you touch anything else
It tells you per port whether PoE exists and at what Type. Thirty seconds from the CLI or the vendor app and it ends the argument before anyone climbs a ladder.
If that doesn’t do it
Compare the powered ports against the datasheet port map
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Step 2: List every port currently powering anything and look for the pattern
All inside ports 1 to 8, all on one card, all on one half of the chassis: that is a capability boundary, not a fault. Check it against the datasheet port map for that exact SKU.
If that doesn’t do it
Check the module and licence state
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Step 3: Check the chassis inventory for the PoE module and the licence state for PoE
A module that is missing, failed or in an unsupported slot, and an unapplied or expired licence, both present identically: a port that quietly does nothing and logs nothing.
If that doesn’t do it
Check global inline power and any power policy
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Step 4: Check whether inline power is enabled globally and whether a policy or template has turned it off
No power anywhere on the switch points here rather than at any one port. Look for a template applied at provisioning; this is common on switches that were staged offsite.
If that doesn’t do it
Confirm you are not on an uplink or combo port
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Step 5: Confirm the PD is not patched into an uplink, combo or SFP-adjacent port
These link and never power, which is exactly the symptom. Trace the actual patch rather than trusting the panel label.
If that doesn’t do it
Move the PD to a capable port and document the constraint
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Step 6: Move the PD to a capable port, then write the constraint down where the next person will find it
Label the non-PoE ports on the panel, or put it in the port description field on the switch. This fault returns every time anyone adds a device, and a one-line description is the entire permanent fix.
If that doesn’t do it
Escalate to design: the switch does not have enough PoE ports at the right Type for the device count
References
- IEEE 802.3-2022 Clause 33
- IEEE 802.3-2022 Clause 145