IT Pro is supported by its audience. When you purchase through links on our site, we may earn an affiliate commission. Learn more

If the Qnap TS-251B looks a little like a miniature PC, there’s a reason: it practically is. Not only does it have a dual-core Intel Celeron J3355 processor and 4GB of RAM, but an HDMI video input, a set of three audio outputs and three USB 2 ports for plugging in a keyboard and a mouse. It even has a PCIe expansion port where you can install a 10GbE network card, a Qnap dual-port M.2 card for NVMe SSDs, a USB 3.1 Gen 2 card or a wireless network card. 

These features come into play when you explore the software. On the one hand, Qnap’s HybridDesk Station software gives you a pared-back desktop UI for browsing the internet or playing music, video and photos direct from the NAS to your TV via the HDMI output. On the other hand, the optional Linux Station app allows you to use the NAS as a Linux desktop, running Ubuntu and apps from the Ubuntu app store. Don’t go crazy – while powerful for a NAS, the TS-251B makes a relatively weedy PC – but it makes the TS-251B a versatile appliance that can do a bit more than the usual tasks through the browser or else fill in as a PC in a pinch.

As a NAS, it’s got a lot going for it. Slide the catch up on the left-hand side and the front panel slides off to reveal the two drive bays, which use Synology-style slide-in caddies to make populating and depopulating easy. The design is a good fit for use near or under a TV, and the TS-251B is impressively near-silent when idle, running at under 17dB. However, there’s a fair bit of clatter from the drives when it’s working hard, and we found that our Western Digital Red drives ran surprisingly warm during testing. While this didn’t cause any issues, we could feel the heat when we pulled them from the chassis. 

With drives installed, the setup process is fairly straightforward; the step-by-step wizard takes you through configuring user access, date and time and the basic file transfer services, setting up the storage pool and adding multimedia functions. After that, you can set up users and shared folders and install apps from Qnap’s comprehensive app store. It has clearly focused a lot of time and energy on its software, which now feels close to Synology’s in terms of user-friendliness and access to management tools. 

But there are still some rough edges, such as the way the dashboard reported that there was no storage pool setup when we had one up and running, or the way that the user interface grew unresponsive at one point until we restarted the NAS and logged back in. We didn’t experience anything that signalled a serious issue, but Synology’s software still has a slight edge.

All the same, Qnap is giving it some stiff competition when it comes to apps and features. Not only do you get all the usual applications for backup, file-sync and surveillance, along with Qnap’s Dropbox-like Qsync, but retro games console emulators, Docker container support, development tools, CMS and CRM apps, a chat server, virtualisation and a lot more. The software isn’t flawless – we had some problems getting our test playback devices to recognise Qnap’s media server, though they had no problems with a Plex server on the same NAS. 

With a decent spec behind it, the TS-251B can be a good performer. In our backup tests, it wasn’t as fast as the Asustor and Synology, but it’s ahead of the chasing pack. However, the sequential read and write speeds aren’t as competitive, meaning the TerraMaster F5-221 and Western Digital MyCloud DL4100 pull ahead. 

Still, raw performance isn’t everything, and the Qnap has good enough file transfer speeds and adequate horsepower to keep it in the race. Most of all, it gives you a strong set of media NAS features for a reasonable price. If you can’t stretch to the Asustor AS5304T, this is a credible low-cost alternative.

Qnap TS-251B-4G specifications

Model number


Price (inc VAT)

£314 (£377)


2yr RTB

Dimensions (WDH)

105 x 226 x 168mm

Noise level



Intel Celeron J3355

CPU cores

Dual core

CPU speed, cores

2GHz to 2.5GHz

RAM/maximum RAM


Bays (free)

2 (2)

Drive type

3.5in SATA 6Gb/s hard disk

Max internal capacity


RAID modes

JBOD, 0, 1

Bay type

Slide-in caddy

Hot swap?


2.5in drives supported


SSD support


Status display

5 x status LEDs

Gigabit Ethernet ports


10GB Ethernet ports


USB ports (rear)

USB 3, 3 x USB 2

USB ports (front)



HDMI, 3 x audio

802.3ad link aggregation


Load balancing


Network failover


Major network protocols


iSCSI target


USB expansion options


NAS OS/firmware


Main desktop software

Qfinder Pro, Qsync

Remote access


Cloud integration

Cloud Storage backup to AWS, Azure, Dropbox, Google Drive sync


Rsync server, Time Machine


Photo Station, Music Station, Video Station, iTunes Server, Plex, OceanKTV


Surveillance Station, QVR Pro, QVR Centre, QVR Guard

Testing and Development

Container Station, web server

Other major services

Virtualization Station, QVPN Service, Notes Station, HybridDesk Station, Linux Station, IFTTT agent

Featured Resources

Big data for finance

How to leverage big data analytics and AI in the finance sector

Free Download

Ten critical factors for cloud analytics success

Cloud-native, intelligent, and automated data management strategies to accelerate time to value and ROI

Free Download

Remove barriers and reconnect with your customers

The $260 billion dollar friction problem businesses don't know they have

Free Download

The future of work is already here. Now’s the time to secure it.

Robust security to protect and enable your business

Free Download

Most Popular

The human brain is far more complex than AI researchers imagine
artificial intelligence (AI)

The human brain is far more complex than AI researchers imagine

17 Sep 2022
How to secure your hybrid workforce
Advertisement Feature

How to secure your hybrid workforce

23 Sep 2022
What your hybrid workforce needs from their laptops
Advertisement Feature

What your hybrid workforce needs from their laptops

21 Sep 2022