Asustor AS5404T Nimbustor NAS Review UK (2026) – Tested

Here’s the thing about network storage: most people either buy too much NAS for their needs, or they buy something that’ll bottleneck them in 18 months. I’ve spent several weeks with the Asustor AS5404T Nimbustor 4, pushing it through everything from 4K video editing workflows to game library hosting, and I reckon I’ve worked out exactly who this is for (and who should absolutely skip it).

But does it actually deliver? Let’s get into what I found after pushing this thing through several weeks of real-world use.

But here’s where Asustor made an interesting choice: four M.2 slots instead of traditional 3.5″ bays. This means you’re buying SSDs (not included), which gets expensive fast. A 2TB NVMe drive runs around £100-150, so you’re looking at £400-600 just for storage on top of the NAS itself. That’s a significant investment, but the performance gains are substantial.

One feature I particularly appreciated: the HDMI 2.0 port. You can connect this directly to a monitor and use it as a basic HTPC. It’s not something I’d use daily (the interface isn’t optimized for this), but it’s handy for troubleshooting without needing another device.

Look, the performance numbers tell most of the story here. This thing is properly fast. I edited 4K video directly from the NAS using DaVinci Resolve, and it felt like working from a local drive. That’s the M.2 NVMe advantage right there.

But (and this is important), you need the right network setup to see these speeds. If you’re still running gigabit ethernet, you’ll be capped at around 110-115 MB/s. The AS5404T needs 2.5GbE or better to stretch its legs. I tested with a QNAP QSW-1105-5T switch, and that’s when things got interesting.

Thermal performance was excellent. Even during extended stress testing, the drives stayed below 50°C and the fan remained nearly silent. The aluminium chassis acts as a passive heatsink, which is clever engineering.

Installing M.2 drives is genuinely tool-free. You slide out the tray, clip in your SSD, and slide it back. Takes about 30 seconds per drive. Compare that to traditional NAS units where you’re faffing about with drive caddies and screws.

My only gripe? The front power LED is absurdly bright. If this sits in your bedroom or living room, you’ll want some electrical tape over that thing. It’s like a tiny blue lighthouse at night.

The ADM operating system is… functional. It does everything you need, but the interface feels about five years behind Synology’s DSM. Icons are dated, some menus are nested too deeply, and there’s inconsistent terminology in places. It’s not bad, just not as polished as the competition.

That said, the app ecosystem is solid. Plex, Docker, VPN server, cloud sync – all the essentials are there and work reliably. I particularly liked the mobile app (AiMaster), which gives you proper control over the NAS from your phone, not just basic monitoring.

Synology’s DS423 is the elephant in the room. It’s cheaper, the software is significantly better, and the ecosystem is more mature. But you’re limited to gigabit ethernet and a weaker processor. For basic file storage, it’s brilliant. For performance-intensive work, it’ll hold you back.

Personally? If you’re already invested in Synology’s ecosystem and don’t need the speed, stick with them. But if you’re starting fresh and need proper performance, the Asustor makes more sense at this price point.

Here’s my honest take on value: this is expensive, especially once you factor in SSDs. But it’s not overpriced for what you’re getting. The performance is genuinely excellent, the build quality is solid, and it’ll handle demanding workloads for years.

If you’re just backing up photos and documents, this is massive overkill. Buy a Synology DS124 and save yourself £300. But if you’re editing video, hosting game libraries, or running a small business, the AS5404T’s performance advantage is worth the premium.