Terramaster F4-425 Pro review: Cost, specs, performance

The TerraMaster F4-425 Pro is a compact four-bay NAS that punches above its price class, with an eight-core Intel chip, three M.2 slots, and dual 5GbE networking, at the cost of a few real but manageable caveats.

NAS devices have evolved well beyond simple network drives. They now run media servers, security camera systems, and containerized apps, all from one box on the home or office network.

TerraMaster pitches the F4-425 Pro squarely at that all-in-one role. It pairs a decently powerful Intel chip with unusually flexible storage for the class and price point.

I reviewed the smaller two-bay F2-425 in late 2025. The F4-425 Pro sits above it with more bays, a faster processor, a triple M.2 design, and upgraded system software.

TerraMaster F4-425 Pro review: Specifications

TerraMaster F4-425 Pro review: Design

The F4-425 Pro uses a two-tone enclosure, with a black drive-bay face set against a silver body. The four bays are accessed from the front, with tool-free trays for installation.

It measures 5.9 by 7.1 by 8.6 inches and weighs 6.4 pounds without drives. That is a compact footprint for a four-bay unit with this much expansion inside.

Build quality is solid. On NAS devices in this class from other vendors, we’ve seen stripped screws and imprecise material line-up. As with the rest of Terramaster’s products, this is not the case.

TerraMaster F4-425 Pro review: iPad for scale

The front carries a power button, a USB port, and status indicators. A single 120mm fan sits at the rear, with several speed modes available in software.

TerraMaster rates idle noise at 20.9 decibels, measured with four drives in standby. Real-world noise under load is higher and depends on the drives fitted.

We tested the unit with four 4TB Seagate Red drives. We also used four 24TB WD Red Pro, that retail on Amazon with a price that seems to vary by day.

Under load, which is mostly drive chatter, the unit hit about 39 decibels one meter away with either drive array. Good enough.

TerraMaster F4-425 Pro review: Storage and the triple M.2 design

The headline storage feature is the three M.2 NVMe slots, which is unusual for a four-bay NAS. Most competitors offer one or two.

Each M.2 slot supports up to 8TB, and the four SATA bays each take drives up to 30TB. TerraMaster lists a maximum total capacity of 144TB across all seven drives.

There is an inconsistency in TerraMaster’s own materials worth noting. The datasheet text claims 144TB total, while the specification table lists the SATA bays at 120TB raw and the M.2 slots separately, which only reach 144TB when both are combined.

TerraMaster F4-425 Pro review: Simple but functional drive sleds.

The three M.2 slots can be set up as a RAID 5 array. This is a genuinely useful option, allowing a fast SSD pool with redundancy separate from the main hard drive bays.

One caveat sits in the spec sheet. The M.2 slots run at PCIe 3.0 x1, which is a single lane each. That limits the peak speed of each SSD well below what a typical Gen3 x4 NVMe drive can deliver. This is fine, as one drive at the x1 allocation is still about 6 gigabits per second read and write.

We’ve said it before, we’ll say it again. M.2 storage in a 10-gigabit Ethernet NAS is overkill. It’s super-overkill here with 5 gigabit Ethernet, which can be saturated with the hard drives in a striped RAID.

For RAID across the main bays, the unit supports the full range from JBOD up to RAID 10. It also offers TRAID, TerraMaster’s flexible array system that mixes redundancy with easier capacity expansion, similar in concept to Synology’s Hybrid RAID.

TRAID is solid enough, assuming you’re going to stick with Terramaster hardware if you ever upgrade. It works the way it says it will, with easy, albeit time-consuming, addition of drives to the enclosure.

TerraMaster F4-425 Pro review: Connectivity

Networking is handled by two 5-gigabit Ethernet ports. This is an unusual middle ground, sitting above the common 2.5GbE but below the 10GbE found on higher-end units.

The two ports support link aggregation and bonding. TerraMaster claims real-world write speeds up to 1010 MB/s when combined with SMB Multichannel. We didn’t quite see that, even with three SSDs.

On a dedicated wired to wired network between the F4-425 Pro and a M1 Ultra Mac Studio with link aggregation, we saw about 800 megabytes per second. Close enough.

TerraMaster F4-425 Pro review; A rear view.

For external connections, there are three USB-A 3.2 Gen2 ports and one USB-C 3.2 Gen2 port, all rated at 10Gbps. These handle external drives, backups, and direct media imports.

An HDMI port is present, but TerraMaster states it is for displaying system management output rather than media playback. This is a notable limitation for anyone hoping to use it as a direct-attached media player.

For Mac users, TOS supports Time Machine backups over the network. Setup is simple, with old instructions that still work here.

The F4-425 Pro also supports AFP and SMB, both of which macOS handles natively.

TerraMaster F4-425 Pro review: Processor and memory

The F4-425 Pro runs an Intel N305, an eight-core, eight-thread chip that bursts up to 3.8GHz. This is a strong processor for a NAS in this class, well above the budget chips common at this size.

The chip includes integrated graphics with hardware transcoding for H.264, H.265, MPEG-4, and VC-1, up to 4K at 60fps. That makes it well suited to running Plex, Emby, or Jellyfin media servers.

Using a Plex server across our local network, we were able to transcode five 4K streams to 1080p without frame loss. Pretty good.

Geekbench single-core results for the TerraMaster F4-425 Pro and the M1 and M4 versions of Mac mini.

To be fair, we never really expect that much in terms of performance from a NAS. The exceptions are when the NAS is intended to perform double-duty with server applications as well as being a storage appliance.

Under Geekbench, the F4-425 Pro manages a 1,313 single-core score. It’s certainly not going to fare well against the M4 Mac mini or even the M1 Mac mini, but it’s still capable of performing tasks.

Geekbench multi-core results for the TerraMaster F4-425 Pro and the M1 and M4 versions of Mac mini.

It’s a similar story when we turn to multi-core testing. Yes, the TerraMaster gets to 4,702 in Geekbench, but the M1 Mac mini scores twice as much.

These graphs are not to mock the F4-425 Pro. Instead, they are here to praise it.

Do not expect blistering-fast server performance from a NAS except in rare circumstances, on hardware that rivals a MacBook Pro in cost. But here, it’s certainly got the grunt to get things done in the background.

As with most “pro”-grade NAS devices, Docker containers are one of the best ways to extend what this hardware can do. The RAM is a bit of a constraint here, with the new TOS 7 taking up about 3GB of that in daily use.

Memory is where the unit shows a limit. It ships with 8GB of DDR4 in a single SODIMM slot, expandable to 32GB, but it is non-ECC and there is only one slot.

The single memory slot means upgrading requires replacing the existing module rather than adding to it. The lack of ECC is normal at this price, but worth noting for users storing critical data.

TerraMaster F4-425 Pro review: Software, AI, and TOS

The F4-425 Pro runs TerraMaster’s TOS operating system. TerraMaster heavily promotes TOS 7 as “the world’s first AI-native NAS operating system,” built around natural-language control. The marketing claims are extensive, describing voice and text commands handling over 90% of operations.

Sure. It can help, but in testing, the natural-language controls worked for basic tasks but did not meaningfully reduce setup complexity. And, I think uGreen beat them to the punch with the world’s first AI-native NAS operating system,

TerraMaster’s on-device photo AI remains usable but not a reason to switch away from Apple Photos or Google management.

The more grounded app story is strong. TOS supports Docker, virtual machines via VirtualBox, and a wide range of apps including Plex, Emby, and the major download clients.

A built-in Surveillance Manager app connects to ONVIF-standard IP cameras for local recording and playback. This works fine, but is otherwise unremarkable. Most won’t use the app.

TerraMaster F4-425 Pro review: A feature-rich box with caveats to verify

The F4-425 Pro packs an unusual amount into a compact four-bay NAS. The eight-core Intel chip, triple M.2 slots, and dual 5GbE networking are all strong for the class.

Its closest internal reference point is the smaller F2-425 that I reviewed previously. The F4-425 Pro scales that up with more bays, more M.2 expansion, and a more capable processor.

TerraMaster F4-425 Pro review: The rear ports and fan

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The cautions are mostly around marketing versus reality. The AI claims are bold, the PCIe 3.0 x1 M.2 lanes limit SSD speed, and the single non-ECC memory slot caps expansion. This is all okay for the price point and the target user.

For Apple households, TOS handles Time Machine, AFP, and SMB, and the strong media transcoding suits a Plex or Infuse setup. It is not an Apple product, but it slots into an Apple home network without trouble.

TerraMaster F4-425 Pro Pros

• Eight-core Intel N305 with 4K transcoding
• Three M.2 slots, configurable as RAID 5
• Dual 5GbE networking

TerraMaster F4-425 Pro Cons

• M.2 slots limited to PCIe 3.0 x1
• Single, non-ECC memory slot
• HDMI is management-only, not for media playback

Rating: 4 out of 5

The TerraMaster F4-425 Pro is a solid piece of hardware, that performs well enough. The RAM is a constraint, but only if you’re planning on running a lot of services from the box.

It’s not the fastest NAS, it doesn’t have the largest potential capacity of units we’ve reviewed. What it does is deliver a solid hardware and software package at a fair price, with no roadblocks for Apple hardware users.

Where to buy the TerraMaster F4-425 Pro

The TerraMaster F4-425 Pro is priced at $639.99 from TerraMaster’s online store with 16GB of memory, down 20% from $799.99. Its 8GB memory variant is available for $559.99, again discounted from $699.99.

It is also available from Amazon, with the 8GB at $699.99 and the 16GB at $799.99. Again, a 20% coupon is available at the time of publication, making the prices comparable to TerraMaster’s online store.