The TerraMaster F4-424 has competent hardware and the quad-core Intel Processor N95 appears to be a good solution for a higher-end consumer NAS. It's nice to see that TerraMaster didn't cheap out on the RAM side and included 8 GB as the default amount of memory. This will allow the F4-424 to be used to the full extent of its capabilities without the RAM needing to be upgraded, especially for things like docker or other types of virtual machines. The SSD caching options, using the M.2 slots might not bring a lot of extra performance in most consumer usage scenarios though and the 2.5 Gbps Ethernet interface is also a limiting factor when it comes to taking full advantage of the addition of SSDs. However, we were in all fairness unable to test the potential performance improvements of bonding the two Ethernet interfaces, as the adaptive load balancing mode didn't appear to offer any performance benefits and as we didn't have access to a manged switch, we couldn't test the LACP mode.

The general low operating noise of the F4-424 also means that it's suitable for a home environment, but unfortunately, TerraMaster hasn't taken advantage of the HDMI interface, so you can't plug the F4-424 into a TV or display as a media player, which is a missed opportunity. Sadly things go a bit downhill from here, as the F4-424 isn't as power efficient as we expected, and it doesn't appear to go down into a power saving/sleep mode when not being accessed for long period of times. Add to this the fact that SSDs with heatsinks can't be used, some performance issues that we couldn't figure out and the bugs that we came across in our testing, and it's starting to feel like this was a rushed product. As pointed out in the review, the 2.5 Gbps Ethernet is holding the hardware back, especially when used with an SSD. However, a faster network interface such as 10 Gbps would've meant a more costly device, as well as the added cost of a 10 Gbps capable switch. The market is also full of NAS appliances with only Gigabit Ethernet that offer SSD support and just like its competitors, TerraMaster sells a range of other devices for those that are looking for faster network attached storage. The Intel Processor N95 is also something of a limiting factor when it comes to SSDs, as it only sports nine PCIe 3.0 lanes, which means SSDs are not just limited by the PCIe revision, but also by the lane width available. In all fairness though, the Ethernet interface is still the bigger issue here, but we just want to make sure to set the expectations right from the start, if you consider buying one of these NAS appliances.

The F4-424 is by no means a bad product, but TerraMaster really must address the software related issues we came across during our testing for us to be able to recommend it. We should not that we're working on a review of another NAS from TerraMaster with TOS 6 and it appears that the new OS release has resolved the bugs and performance issues we experienced with the F4-424. TOS 6 is in the final stages of beta testing and should be available for many of their products later this autumn. With an MSRP of US$500 it is competitively priced compared to the competition, especially as TerraMaster is a CPU generation or two ahead of its competitors if we compare with other 4-bay NAS appliances with a similar feature set. We would've liked to have recommended the TerraMaster F4-424, as the hardware is solid, but sadly there were a few too many issues that we ran into, to be able to do so with a clean conscience.