Best answer: No, the ASUSTOR AS6508T is not a good NAS for Plex, simply because its Intel processor is too weak for transcoding.
Not the best from Intel
Intel’s Atom C3538 (clocked at 2.1Ghz) isn’t a particularly powerful processor. It’s 64-bit, has multiple cores, and doesn’t have an issue with maintaining its rated clock speed, but there simply isn’t enough performance here for 4K on Plex. Unfortunately, the ASUSTOR AS6508T has this processor, making the NAS for Plex a hard sell.
The issue with the ASUSTOR AS6508T is that it’s an incredibly capable NAS aside from the CPU. I’m talking dual 2.5Gb and 10Gb LAN ports. That’s madness for a consumer-grade NAS for the home and small office, but all these features are focused on file storage as opposed to media consumption.
One should aim for an Intel Celeron CPU at the very least. The latest Celeron processors in NAS models are capable of transcoding even 4K content without much of a stutter, though that’s a single stream mind you. This isn’t something you can hope for with NAS models that rock six bays or more. The majority of them come with this lesser CPUs.
Choosing the right NAS for Plex
Picking up a better-equipped NAS for Plex is a must if you plan on streaming plenty of 4K content. Pick a smaller NAS with up to 6 bays, and you should be able to score a decent Intel CPU. Something like the Synology DS1019+ would be a better fit. You only sacrifice three bays, still allowing you to install plenty of storage capacity.
This NAS, for instance, has an Intel Celeron J3455 CPU (clocked at between 1.5 and 2.3 GHz) and is a much better fit for Plex playback. It even supports 4K transcoding with positive results. This NAS also supports expansion, so don’t worry if you feel the five bays a little restricting to begin with.