The PoE budget trap waiting in your Wi-Fi 7 refresh

Here is a failure mode that is almost invisible in monitoring and expensive to fix after the fact.

A Wi-Fi 7 access point with three radios and a multi-gigabit uplink typically wants 802.3bt — PoE++ Type 3, up to 60 W — to run everything at full capability. Plug the same AP into an 802.3at (30 W) port and it will not fail. It will boot, join the controller, show as healthy, and serve clients.

What it will also do, depending on vendor and model:

• Disable the 6 GHz radio entirely, or run it at reduced chain count.
• Drop the uplink from 5 GbE or 2.5 GbE to 1 GbE.
• Reduce the number of spatial streams.

Some vendors log this clearly. Several report it only as a low-priority informational message that nobody reads.

How to avoid it

Read the right number on the data sheet. Every AP data sheet quotes a minimum power requirement and a full functionality requirement. The second is the one you procure against.

Budget the switch, not just the port. A 48-port switch advertising 802.3bt rarely delivers 60 W on all 48 ports at once. Forty APs at 45 W is 1800 W before phones, cameras and door controllers.

Check the cable. 802.3bt Type 3 uses all four pairs and dissipates meaningful heat in the bundle. Cat6A in sensible bundle sizes is the safe answer.

Verify after install. Pull the negotiated power class and actual link speed for every AP and compare against expectation. A five-minute script finds these instantly.

The Ubiquiti exception worth knowing

The UniFi U7 Pro runs on standard 802.3at, which is unusual for a tri-band Wi-Fi 7 access point and is a genuine practical advantage — an existing PoE+ switch estate can often carry it unchanged. The U7 Pro Max draws more, so check before mixing them.

The wider point

The Wi-Fi 7 upgrade is not really a wireless project. It is a switching and cabling project with new access points at the end of it. Scope it that way from the start and the project goes fine. Scope it as "swap the APs" and you will find out about the switching in month four.