TerraMaster F4-425 Plus short test: Flexible, metal-housed design, minor issues

The TerraMaster F4-425 Plus earns points for its solid metal housing, quiet fan, and especially its versatile feature set. Four hard drives, three SSDs, four fast USB ports, and two 5-Gbps Ethernet ports make a strong impression.

The weak spot is the processor. The Intel N150 is fast enough for backups, most Docker applications, and running the F4-425 Plus as a media server, but compute-heavy apps like Immich process data more slowly, and virtual machines push the NAS to its limits.

TOS 6 is easy to set up, but anyone wanting to manage more than files, backups, and media will quickly end up relying on Docker. The operating system still has minor bugs, but it proved stable in testing. For users looking for a flexible NAS for backups, file syncing, or media server use, the TerraMaster F4-425 Plus is an easy recommendation.

The TerraMaster F4-425 Plus NAS is currently available on Amazon for $455.99 during Cyber Monday, reduced from its $569.99 list price. The comparable TerraMaster F2-425 Plus, which offers two drive bays instead of four, is priced at $399.99.

Like many competitors, the TerraMaster F4-425 Plus NAS uses an Intel Processor N150. Even so, the device stands out: with three M.2 PCIe SSD slots, four high-speed USB ports, and dual 5-Gbps LAN connections, it offers features that are unusual in this price range.

Processor: Intel Processor N150 4 x 3.6 GHz, 6W PL1, Intel Twin Lake

Graphics: Intel UHD Graphics 24EUs (Alder Lake-N)

RAM: 16 GB DDR5-4800 (1× SO-DIMM), expandable to 32 GB

Ports: 1x USB-C (10 Gbit/s), 3x USB-A (10 Gbit/s)

Network: 2x LAN (5 Gbit/s)

Storage: 4x 3.5" HDD (SATA), 3x M.2 SSD (PCIe 3.0 x1, 8 Gbit/s)

Dimensions (H × W × D): 150 × 181 × 219 mm (5.91 x 7.13 x 8.62 in)

Weight: 2.9 kg (6.4 lbs.)

Power supply unit: 90 watts

Price: $569.99

The new TerraMaster F4-425 Plus resembles the F4-425, but with a metal chassis and a smaller TerraMaster logo. The aluminum enclosure doesn’t just look more premium; it also raises the weight from 2.1 to 2.9 kilograms. Build quality is excellent, although the drive trays remain plastic and the rear panel is plastic as well. Status LEDs for the M.2 SSDs are notably missing, so a failed SSD can only be detected through the software.

Beyond the improved construction, the Plus model introduces several substantial upgrades. Most importantly, it now connects to the home network via dual 5-Gbps Ethernet ports, which can be used simultaneously for a combined bandwidth of 10 Gbps. In practice, the NAS can be up to four times faster than its predecessor.

TerraMaster uses a more modern, though only moderately powerful, Intel Processor N150 and equips the device with 16 GB of RAM out of the box. The memory can be expanded to 32 GB via a single DDR5-4800 SO-DIMM. The biggest improvement, however, is arguably the added flexibility from the expanded storage options.

Four drive bays are almost standard for a NAS in this price class. What sets the TerraMaster F4-425 Plus apart is that it doesn’t stop at one or two M.2 slots, but offers three. This allows the SSDs to run in a RAID 5 configuration, so the system can keep operating without data loss even if one of the drives fails.

The HDDs and SSDs form two separate storage pools, which makes sense given their different speeds. Each SSD is connected via PCIe 3.0 x1, limiting read and write speeds to about 1 GB/s. Even entry-level SSDs can saturate that connection, and since the NAS is capped at roughly 1.25 GB/s over its two 5-Gbps LAN ports, the modest PCIe bandwidth isn’t a meaningful drawback in real-world use.

The USB selection is also impressive for this price. TerraMaster includes three USB-A ports and one USB-C port, all rated at 10 Gbps. This makes it easy to integrate external drives into the network through the F4-425 Plus, for example to use a USB hard drive for automated Time Machine backups.

Altogether, the system layout allows storage to grow gradually: start with one or two HDDs, expand to three or four, then add capacity through the M.2 SSDs and external drives as needed. In testing, TOS 6 handled this cleanly. It managed a single HDD without issue, then mirrored it to a second drive in RAID 1, and later expanded the array to RAID 5 with a third HDD - a process that took more than 24 hours with 6 TB drives. The NAS supports up to 144 TB in total, using four 30 TB HDDs and three 8 TB SSDs.

TerraMaster relies on its in-house operating system, TerraMaster Operating System 6 (TOS 6). The Linux-based platform is relatively user-friendly: installation and setup take only a few clicks through the companion smartphone or PC app, and most features don’t require any advanced technical knowledge.

TOS 6 provides clear monitoring of CPU and RAM usage and shows the temperatures of both the processor and drives. TerraMaster includes its own app store with free applications for turning the F4-425 Plus into a photo or media server, among other roles. Plex and Jellyfin can also be installed directly from the store. Additional third-party tools can be deployed via Docker; in testing, Immich installed and ran without issue.

Alongside a file manager and disk management tools, TOS 6 includes a backup application that can create backups to cloud storage or USB drives, offer a Time Machine volume for macOS, or synchronize folders. TOS 7 is expected to expand the feature set further with additions like a multi-tab file explorer and built-in virtual machine management.

TOS 6 remained stable throughout testing and never crashed, but it isn’t free of quirks. USB drives sometimes receive new names when unplugged and reattached, which breaks Time Machine backups until they’re set up again. The system utilization data shown on the desktop doesn’t always match the values in the settings. Some system notifications refuse to clear. The settings menu isn’t especially intuitive, and the “community apps” section of the app store feels disorganized.

The TerraMaster F4-425 Plus comes exclusively with an Intel Processor N150. Although the chip only launched in early 2025, its four efficiency cores, boost speeds up to 3.6 GHz, and 6-watt power budget make it only moderately powerful.

In testing, the Intel N150 proved fast enough for many typical NAS workloads. TOS 6 feels responsive, and simultaneous backups and file transfers from multiple devices run without issues. More demanding tasks, however, require patience. Processing 312 photos at 60 megapixels in Immich took roughly 85 minutes in our test. Even during file copies to the NAS, the processor sits at around 20 percent utilization.

Thanks to the single large fan, the frugal Intel chip stays at a harmless 61 °C even under sustained load. The fan speed can be adjusted manually, though it’s rarely necessary given the low temperatures and the barely audible noise level.

The TerraMaster F4-425 Plus is a highly versatile NAS offered at an attractive price. It’s well-suited for users who mainly need network storage for backups, media, and a handful of Docker apps. Those who plan to run virtual machines or support many simultaneous client connections should look to a more powerful model instead.