The Ubiquiti Flex Mini 2.5G has been highly requested for review on STH since we launched the Ultimate Cheap Fanless 2.5Gb Switch Buyer’s Guide. This is a 5-port 2.5GbE switch also known as USW-Flex-2.5G-5. Low power, PoE-in and UniFi management make it quite different. At the same time, we opened it up and found that it was the same internal chipset that powers some 4-port 2.5GbE and 2-port 10G switches priced under $30 that we hadn’t seen anyone detail about before.
As a quick note, we purchased these units thanks to our STH YouTube members. We have “refused to sign”effective testing nda“With Ubiquiti what everyone else does Because there is a line that Ubiquiti will not allow us to remove, saying that we can review the product provided Ubiquiti is allowed to review the post before publishing, and we will include that response if necessary. While we visit data centers, manufacturing sites, and similar locations and let people preview to make sure we are not leaking confidential information, we do not allow vendors to preview and provide concrete feedback that we would need to include in our reviews. Our readers and YouTube viewers have requested that we review this box for years, so we purchased a few to provide honest evaluations. As a side note, when Patrick was out at Microcenter this week purchasing spare units, one of the YouTube viewers said hello and commented on my recent Ubiquiti Unifi Cloud Gateway Fiber UCG-Fiber review.
Patrick’s Editor’s Note, Ubiquiti reached out the evening after it was published and requested an edit to the above paragraph. Although obviously remember Ubiquity told me that everyone else signs an “Influencer Testing NDA”, there may be people who haven’t done so, so we’re going to eliminate that. Fair point. We also changed “Standard NDA” to “Influencer Testing NDA” because Ubiquiti also stated at the time of the request that they were not aware of the review and included the feedback language in the question. In doing so, he impersonated the person at Legal who had actually e-mailed me the document and with whom I had discussed my concerns. In 16+ years of reviewing products in the industry I have never received a request like this, especially when we are purchasing products for editorial review.
If you’re just looking for purchase links, you can find them at B&H Photo (affiliate link).
Ubiquiti Flex Mini 2.5G Hardware Overview
The switch has five 2.5GbE ports as a headline feature. What Ubiquiti is doing is making the profile of the switch minimally larger than the port.
Powering the switch can happen on the 5th port, which is PoE IN or USB Type-C 5V power input. As a quick labeling note, it would have been nice for Ubiquiti to label it as port “5” to match the other four.
The first thing you should notice about the Flex Mini 2.5G is its size. At just 4.6×3.5×0.8 inches or 117.1x90x21.2 mm this is a very small switch.
In fact, the plastic housing makes it one of the smallest switches in its category. This presents huge challenges that we will face when we come in.
There are no vents on the sides of the Switch, so there are no obvious vents on the plastic case.
At the top we find the Ubiquiti logo.
Here is the bottom of the unit. There are nice rubber feet placed, but if you’re thinking they’re hiding the screw to open the case, you’d be wrong. This is another snap together design from Ubiquiti.
You will see a reset button at the bottom. This switch presses a small reset button on the bottom of the PCB.
On the cooling side, Ubiquiti faces a challenge. It has a chassis with virtually no airflow, and is made of plastic, which limits the amount of heat emitted by the chips into the environment. Instead of just using a metal chassis and small heatsink like other devices, the Ubiquiti has a custom heat spreader that makes contact with larger chips and helps cool them. Fortunately it is a low-power device.
There’s something really cool here. Realtek RTL8372N is the big switch chip. This is the same switch chip that drives many 4+2 (4-port 2.5GbE and 2-port 10G) switches on the market because it has two 10G SerDes interfaces.
It appears to be the same as the main switch chip in Ubiquiti UCG-fiber as well.
The smaller Realtek chip is the RTL8221B, which is the same one we’ll find in a Ulinka switch going to its 5th 2.5GbE port.
Next, let’s get to the performance.