PoE+ or UPoE? Why the Wrong Switch May Cause Unexpected Wi-Fi Issues

The short answer: If you're powering access points, PoE+ (30W) is no longer sufficient for full operation of most Wi-Fi 6 and Wi-Fi 7 enterprise APs — and the consequences aren’t obvious. Underpowered APs don’t fail to boot; they degrade silently: radios get disabled, spatial streams get reduced, LAN ports get downgraded from 2.5G to 1G, transmit power drops. You may not notice until users start complaining about Wi-Fi. This article covers exactly how much power each major AP requires (Cisco, Meraki, Aruba, Juniper, Fortinet, Arista), what happens at each power level, and how to choose the right switch — including pre-owned UPoE options at a fraction of new channel pricing. 

Did you know that access points can behave differently depending on how much power they are receiving?

👈 To jump to the AP tables, click your OEM

The addition of a new device drawing the smallest amount of power might be enough to reduce an access point's radio functionality, downgrade the network interface between the AP and switch, or even disable an AP altogether.

PoE (Power over Ethernet) budgeting can impact network performance if under budget, or be a source of waste if overbudgeted. The amount of DC power provided by switches (or switch ports) has been rapidly increasing. The introduction of 90W UPoE+ has opened a whole new world of opportunities. Laptops, cameras, sit-stand desks, LED lighting, even refrigerators and air conditioners are all on the brink of being powered by a network switch.

What is PoE?

So, what is PoE?  In short, PoE is simply DC power delivered over copper wire. The younger generation reading this article might not be familiar with a plain old telephone (or POT as we used to call them), but if you are, you know that plugging a telephone into a phone outlet generates a dial tone. This was because 48V DC power was being provided by your phone service provider's switching infrastructure.  The PoE we're talking about is the same thing provided by our switching infrastructure.

The table above shows the different IEEE standardized “types” of PoE that are currently available. In the past, if a deficient amount of power was being provided, the devices wouldn’t power on. As the products have evolved, the manufacturers are building in a certain level of fault tolerance to make sure some services can still be offered with a lesser amount of power.

Real quick, the PoE standard refers to the port capability, not the switch itself. A C9300-48U switch is a UPoE capable switch, but only comes with an 1100W power supply by default. Even adding another 1100W power supply will only allow PoE+ if all 48 ports are used.  With 300W dedicated to other switch services, dual 1100W powers offers a max of 1,800W PoE budget.  That's just 37.5W per port if all 48 ports are providing PoE.  For full UPoE, only 30 of the 48 ports could provide 60W.

Do You Need UPoE?

And so back to my opening question. Do you need UPoE? The answer is probably yes. And if not yet, how long before it is?  

Flexibility - PoE+ as a standard is waning.  There are thousands of network products already requiring more than 30W per port.  If we're purchasing hardware, deploying UPoE switches today may save us from prematurely needing a switch upgrade.  The cost increase from PoE+ to UPoE is small, and we'll be better positioned to handle future requirements which seem almost to be a certainty. 

Supportability - We don't want unusual and sporadic network issues, nor any device that isn't fully functioning.  All APs are coming from the manufacturers with varying behavioral differences determined by how much power is being provided.  Some combination of reduced radios, reduced spatial streams, LAN1 and/or LAN2 ports speed reduced or disabled, transmit power reduced, USB ports disabled.  Aruba already has APs that require UPoE+ (90W) to fully function.  Otherwise, UPoE (60W) is the only standard that will light up every Cisco, Juniper, or Meraki AP without any restrictions.  Aruba has a feature known as Intelligent Power Management (IPM) which allows us to program how our AP might behave without full power, but why?  We're trying to avoid bottlenecks, not create them.  Why not purchase a lower-end AP and save money?

The same sentiment is true with Multi-Gig or mGig ports.  All enterprise-grade APs manufactured after 2024 has network interfaces of at least 2.5G, so why would we plug them into a 1G switch?

Did you know that Edgeium has used C9300 switches with Multi-Gig ports and UPoE at a lower cost than the C9300-48P?  

What Happens if Not Enough Power?

So, what kind of behavioral differences can we expect?  Radios will be downgraded  or disabled, network interfaces will be downgraded or disabled, USB ports disabled, PoE-PD can be downgraded or disabled, etc.  Lets take a quick look at the different OEMs.

Thank you for reading!

Frequently Asked Questions

Can the wrong PoE standard cause Wi-Fi performance issues?

Yes, and it happens more often than most teams realize. When an access point receives less power than its full operational requirement, it doesn’t fail — it degrades silently. Depending on the AP model and power shortfall, you may see radios disabled, spatial streams reduced (e.g., 4x4 MIMO reduced to 2x2), LAN ports downgraded from 2.5G to 1G or disabled, transmit power reduced, and USB ports disabled. These issues typically surface as user Wi-Fi complaints — slow speeds, dropped connections, poor coverage — rather than obvious hardware alerts. PoE+ (30W) is no longer sufficient for full operation of most Wi-Fi 6 and Wi-Fi 7 enterprise APs. UPoE (60W) is the current safe standard for Cisco, Meraki, Juniper, and Fortinet APs.

What happens if my access point doesn’t get enough power?

Access points don’t fail to boot when underpowered — they degrade silently. Depending on the AP model and how much below its full power requirement it is operating, you may see: one or more radios disabled, spatial streams reduced (e.g., 4x4 reduced to 2x2), LAN1 or LAN2 port speeds reduced from 2.5G to 1G or disabled entirely, transmit power reduced, USB ports disabled. These degradations are often not visible in your dashboard without checking per-port power negotiation and AP operational mode. Performance issues may appear as Wi-Fi complaints rather than obvious hardware failures.

What is the difference between PoE, PoE+, UPoE, and UPoE+?

There are four IEEE-standardized PoE types in common enterprise use. PoE (802.3af, 15.4W) is the original standard, adequate for basic IP phones and older APs. PoE+ (802.3at, 30W) was the standard for Wi-Fi 5 era access points and remains common on installed switch estates. UPoE (802.3bt Type 3, 60W) is the current enterprise standard for Wi-Fi 6 and Wi-Fi 7 APs and covers virtually all current-generation enterprise APs except high-end Aruba models. UPoE+ (802.3bt Type 4, 90W) is required for some Aruba AP models and opens up new powered device categories including laptops, cameras, and digital signage.

How do I calculate my PoE power budget?

The PoE power budget on a switch is the total wattage available for all PoE ports combined. To calculate what you need: list every powered device (APs, IP phones, cameras, etc.) and their maximum power draw at full operation. Sum these values. Then add 20% headroom for future devices and redundancy. Be aware that a switch’s PoE standard describes per-port capability, not total budget. A C9300-48U with a single 1100W power supply has approximately 800W of PoE budget after switch overhead, which supports roughly 13 ports at full 60W UPoE simultaneously if all 48 ports are loaded — not 48 ports at 60W.

Which Cisco switches support UPoE?

The Cisco Catalyst 9300 series is the primary access-layer UPoE platform. C9300-48U and C9300-48UXM support UPoE on all 48 ports. C9300-24UX and C9300-48UXG-4X provide UPoE alongside multi-gig (mGig) ports, which is the optimal combination for Wi-Fi 6/7 deployments. The C9200L-48P supports PoE+ but not UPoE — it is not appropriate for environments requiring 60W+ per port. Cisco Catalyst 9400 and 9500 series also support UPoE at distribution and core, but for access-layer UPoE specifically, the 9300 series is the standard.

Can I get UPoE switches from the secondary market?

Yes. Cisco Catalyst 9300 UPoE switches are available as pre-owned hardware from Edgeium at significantly lower cost than new channel pricing. In many cases, a used C9300-48UXM with UPoE and multi-gig ports is available at a lower price than a new C9300-48P (which only supports PoE+). Edgeium tests every unit to 100% of OEM specifications. The PoE circuitry, power negotiation, and per-port power delivery are all validated before shipment. All units come with Edgeium’s lifetime warranty and are available with CovrEDGE maintenance as an alternative to SMARTnet.

What is Aruba Intelligent Power Management (IPM)?

Aruba’s Intelligent Power Management (IPM) is a feature available on Aruba access points that allows network administrators to define how the AP behaves when it receives less power than its full operational requirement. Rather than a default degradation profile, IPM lets you configure which radios, interfaces, or features are prioritized when power is constrained. For example, you can configure an AP to maintain 5GHz radio performance at the expense of the 2.4GHz radio or a secondary LAN port. IPM is useful for environments where UPoE+ (90W) switches are not yet deployed but Aruba APs are in use, but it is not a substitute for providing full power in new deployments.