Pro XG 8 PoE vs Flex 10 GbE: Count the Usable Ports

Choose the Ubiquiti Pro XG 8 PoE when you need to power connected devices or expand beyond four 10GbE connections. Choose the Flex 10 GbE for a smaller network with separately powered equipment, remembering that a 10GbE uplink consumes one of its four fast ports.

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The models compared here are USW-Pro-XG-8-PoE and USW-Flex-XG. Flex 10 GbE is the product also called Flex XG; it is a different switch from the Flex 2.5G PoE.

These are manufacturer specifications, not measurements from this site. Pro XG 8 PoE specifications, Flex 10 GbE specifications.

A NAS and two computers fit the Flex—with an uplink

Count every connection before choosing the Flex. One NAS, two computers and one 10GbE connection to your main switch occupy all four fast ports. Add another workstation and you have outgrown that arrangement.

The Flex’s fifth socket cannot rescue this layout at 10GbE: it is a gigabit port. Ubiquiti’s datasheet explicitly distinguishes that port from the four ports supporting 100Mbps, 1Gbps, 2.5Gbps, 5Gbps and 10Gbps. Flex XG datasheet.

There is a useful alternative if your upstream connection only needs gigabit speed. Connect the router through the gigabit port and reserve all four fast ports for local equipment. Traffic between devices in the same VLAN can stay on the switch; it does not all pass through the router connection. Consequently, a gigabit internet uplink does not automatically limit local NAS transfers to gigabit speed.

That distinction makes the Flex a sensible choice for a small storage network. The question is whether your fast traffic stays between its connected devices or must cross the uplink.

The Pro provides more room to expand. An SFP+ uplink leaves all eight copper ports available; a copper uplink leaves seven. The Flex 10 GbE is the wrong choice for four 10GbE endpoints plus a 10GbE uplink, because it has only four 10GbE ports in total. That is a port-count limitation, not a claim that its individual connections are slower.

Access points need PoE output, not merely PoE input

The Flex’s PoE capability powers the switch itself. It cannot supply power to an access point or camera. Supplying it with a higher-powered upstream PoE port does not create PoE output. Its documented power inputs are PoE+ and USB-C. Flex power specifications.

If you want Ethernet cables to carry both data and power to your access points, choose the Pro. Its limit is 60W per port at the power-sourcing equipment, with 155W shared across the switch. Eight PoE++ ports therefore do not mean eight simultaneous 60W loads: three such allocations alone would require 180W. Pro XG 8 PoE power specifications.

Build the power plan from each device’s documented maximum requirement, including delivery losses where applicable. An access point drawing little power while idle does not prove that the whole installation will fit during startup or heavier operation.

Also distinguish remote power from remote bandwidth. Using the Flex’s PoE input as its sole upstream cable gives you a gigabit upstream connection. A separate connection to a fast port is needed for a 10GbE uplink, even when PoE supplies the switch’s power. The Pro, meanwhile, requires its external power supply; it is not a replacement for a remotely PoE-powered Flex.

The Pro adds capacity, not a faster speed class

The Pro’s larger aggregate throughput figure describes a switch with more ports. It does not mean that a single NAS connection becomes faster than 10GbE.

ServeTheHome tested the Pro using a Keysight traffic generator and recorded 100Gbps of aggregate Layer 1 traffic across ten ports without frame loss, including its 64-byte frame test. That supports the Pro’s ability to handle simultaneous traffic across its port set. ServeTheHome’s Pro XG 8 PoE measurements.

ServeTheHome separately measured the Flex at just under 40Gbps aggregate throughput in its Keysight CyPerf testing. The publication used different test arrangements for the two reviews, so these figures should not be treated as a controlled comparison of latency or application performance. ServeTheHome’s Flex XG measurements.

For one workstation copying to one NAS, check the storage system and both network interfaces before assuming that replacing the Flex with the Pro will accelerate transfers.

Beside a desk, power and cooling matter

The Pro has active cooling: ServeTheHome’s teardown identified two fans. Its testing recorded roughly 19.6W at idle, and approximately 37dBA against a 34dBA room noise floor after startup while running its line-rate traffic test. Those conditions do not establish silence in a bedroom or noise under a full PoE load. Pro hardware inspection, Pro power and noise testing.

For the Flex, ServeTheHome recorded 10.35W with UniFi connected and only the gigabit management connection attached. This is not an equivalent workload to a fully populated switch, but it gives a useful reference for a lightly connected installation. Flex power testing.

Treat those readings as dated test results. Ubiquiti subsequently documented Energy Efficient Ethernet support for the Pro XG 8 PoE in switch firmware 7.5.10; that release note does not quantify the resulting savings. It would be unjustified to promise a fixed present-day power difference from the older measurements. Ubiquiti’s 7.5.10 release notes.

Layer 3 matters when you actually route between VLANs

The Pro can route between VLANs, whereas the Flex leaves that job to another device. This can matter when substantial storage or server traffic crosses network boundaries. It offers no routing advantage for a workstation and NAS communicating within the same VLAN.

There are configuration consequences. Ubiquiti’s Layer 3 routing implementation uses transit VLAN 4040. A third-party gateway must support VLAN tagging and static routes. Ubiquiti also states that switch routing does not perform NAT and that Traffic Identification and dependent features are unavailable on networks managed by the Layer 3 switch. Buying the Pro does not replace an internet gateway. Ubiquiti Layer 3 routing documentation.

Neither switch deserves a blanket warning. The Pro is the broader recommendation for expansion and powered endpoints; consider the Flex when your complete connection plan fits its four fast ports and you already have device power handled. Before ordering, write down the uplink alongside the endpoints—the uplink is the connection most likely to change this decision.