Not the upgrade you want
The DiskStation DS925+ brings several key upgrades, such as dual 2.5 Gigabit Ethernet ports at the back, and a quad-core Ryzen platform. The result is that the NAS has a definite edge over the DS923+ if you need a little bit of additional power, but the gains are overshadowed by a controversial HDD policy. Essentially, you can't use any other brand's HDDs with the DS925+, and that severely restricts your choices. Not being able to use regular Seagate and WD drives, and having to buy costlier Synology-branded hard drives just doesn't make sense, and it ultimately makes the DS925+ a non-starter.
For
- Dual 2.5 Gigabit Ethernet ports
- Powerful hardware
- Good as a Plex server
- Class-leading software
- USB-C extensibility
- Dual M.2 slots can be used as storage
Against
- Heavily limited in what HDDs you can use
- No way to add 10GbE networking down the line
- No hardware transcoding in Plex
Still a great choice
If you have to choose a model from these two, I'd suggest going with the DiskStation DS923+. It uses a dual-core Ryzen platform, but it's plenty fast in daily use, and you get the best software platform around. Although the DS923+ is a few years old at this point, the NAS doesn't have any limitations beyond the Gigabit Ethernet ports, and if you need multi-Gigabit connectivity, you can upgrade to a 10GbE card without a hassle. And considering there are no restrictions around HDD use, the DS923+ makes better sense than the DS925+ — so grab it while it's still available.
For
- Good hardware
- No issues with Plex
- No restrictions with HDD use
- M.2 slots can be used as storage
- Same software as DS925+
Against
- Gigabit Ethernet connectivity as standard
- No transcoding
