Synology DS225+ vs DS425+
The same Synology in two sizes: buy the DS225+ for a two-drive mirror and the DS425+ if you want four bays. Per Synology's spec sheets, both have an Intel Celeron J4125 that hardware-transcodes H.264/H.265 for Plex, 2GB of DDR4 expandable to 6GB (non-ECC), and one 2.5GbE port next to one 1GbE port, and both run DSM, the most polished NAS software there is. The DS425+ adds two more bays, two M.2 NVMe slots for SSD cache and a second fan. Neither is a heavy Docker or VM host, and both are sold by Amazon.com itself.
Spec by spec
Every figure below is from Synology's product pages, read on 8 October 2026.
| Feature | Synology DS225+ | Synology DS425+ |
|---|---|---|
| Drive bays | 2 × 3.5" SATA HDD or 2.5" SATA SSD | 4 × 3.5" SATA HDD or 2.5" SATA SSD |
| CPU | Intel Celeron J4125, 4 cores, 2.0GHz (2.7GHz turbo) | Intel Celeron J4125, 4 cores, 2.0GHz (2.7GHz turbo) |
| Hardware transcoding | Yes, hardware H.264/H.265 | Yes, hardware H.264/H.265 |
| Memory | 2GB DDR4 non-ECC, one slot, to 6GB | 2GB DDR4 non-ECC, one slot, to 6GB |
| Networking | 1× 2.5GbE + 1× 1GbE | 1× 2.5GbE + 1× 1GbE |
| M.2 NVMe | None | 2× M.2 2280 NVMe (SSD cache) |
| USB | 2× USB 3.2 Gen 1 | 2× USB 3.2 Gen 1 |
| Size and weight | 165 × 108 × 232.2 mm, 1.3 kg | 166 × 199 × 223 mm, 2.18 kg |
| Fans and noise | 1 × 92mm, 19.6 dB(A) | 2 × 92mm, 21.6 dB(A) |
| Power (Synology's figures) | 16.98W access, 6.08W hibernation | 28.25W access, 6.10W hibernation |
The real decision: two bays or four
A two-drive mirror (RAID 1 or SHR) gives you one drive's worth of space with one drive of protection: 2×8TB is 8TB usable. Four drives in RAID 5 or SHR give you three drives' worth with the same protection: 4×8TB is about 24TB usable, and you can grow it one drive at a time. That arithmetic, not speed, is the difference between these two boxes. A common plan is to buy the DS425+ and start with two drives. How many bays do you need?
Networking: one 2.5GbE port on both
2.5GbE matters because 1GbE is the real bottleneck in most NAS setups. A 1GbE link tops out around 110–118MB/s of actual throughput — and a single modern hard drive already reads at roughly 180–280MB/s sequentially, so on gigabit you're leaving half the drive's speed on the table, and a RAID array or NVMe cache is throttled even harder. 2.5GbE lifts the ceiling to ~280MB/s, roughly matching one fast HDD and dramatically improving large-file transfers. It's the single most worthwhile 'speed' upgrade for home NAS; 10GbE only pays off with NVMe pools or many-drive arrays. Both boxes have a single 2.5GbE port, so a single client gets the full multi-gig speed on either; the second port is 1GbE. Their predecessor, the DS224+, was 1GbE only. 2.5GbE vs 1GbE, in full.
Drives: what DSM 7.3 allows
These are 2025 Plus models, so they fall under Synology's newer drive policy. Per Synology's policy FAQ (updated May 27, 2026), under DSM 7.3 hard drives and 2.5-inch SATA SSDs that are not on the compatibility list can be used for new storage pools, drives on the incompatibility list are refused, and M.2 NVMe SSDs must be on the list to create a cache or pool. Synology only guarantees full functionality with listed drives. Whatever you buy, use NAS-rated CMR drives such as WD Red Plus or Seagate IronWolf. The drive policy, decoded.
What neither does well
- Headroom. 6GB of RAM is the official ceiling on both, and the J4125 is a 2020-era chip. Fine for files, photos, backups and Plex; tight for many containers; not for VMs.
- ECC. Neither has it. Synology's ECC model is the DS925+, which gives up hardware transcoding. ECC is nice, not mandatory.
- A 10GbE path. Neither has a PCIe slot. If you might want 10GbE later, the QNAP TS-464 has one.
- NVMe on the DS225+. It has no M.2 slots at all. What NVMe cache actually speeds up.
Which should you buy?
Choose the DS225+ if you want a photo, file and backup appliance for a household and two drives' worth of mirrored space is enough. If you want photos, files, and backups working tonight with zero homelab tinkering, this is the box to buy: DSM is the most polished NAS software there is, the DS225+ is the easiest way to get it, and it finally adds a 2.5GbE port.
Choose the DS425+ if you want room to grow, more usable space per drive, or SSD cache. The 4-bay Synology most homes should buy: DSM's polish, room for four drives and a CPU that can transcode for Plex. Power users who need ECC or a 32GB RAM ceiling should look at the DS925+ or the QNAP TS-464 instead.
Either way: RAID is not a backup. RAID (except RAID 0) protects against DRIVE failure — if one disk dies, the array keeps running while you replace it. It does nothing against the things that actually destroy data: accidental deletion, ransomware, file corruption, a failed controller, theft, fire, or a power surge that takes the whole box. All of those hit the live array and every mirror of it at once. RAID is about uptime and availability; a backup is a separate, ideally offline or off-site copy you can restore from. You need both, and 'I have RAID' is the single most common — and most dangerous — misconception in home storage.
Frequently Asked Questions
Decide on bays, not speed: both have the same Intel Celeron J4125, the same 2GB of RAM expandable to 6GB and the same one 2.5GbE plus one 1GbE port, per Synology's spec sheets. Buy the DS225+ if a two-drive mirror is enough for your photos, files and backups. Buy the DS425+ if you want more usable space per drive with RAID 5 or SHR, room to add drives later, or the two M.2 slots for an SSD cache. You can start the DS425+ with two drives and fill the other bays later.
Not in the processor or the network. Both use the Celeron J4125 and both top out at one 2.5GbE link, so a single large file copies at about the same speed on either. The DS425+ can be faster on random access if you add Synology-listed NVMe SSDs as a cache, and a four-drive array reads faster than a two-drive mirror, but the 2.5GbE link caps sequential transfers at roughly 280MB/s on both.
Yes, within limits. The J4125's integrated graphics hardware-transcodes H.264 and H.265, which Plex uses with a Plex Pass and Jellyfin uses for free. The limits are RAM (2GB base, 6GB maximum) and a 2020-era chip, so plan on a handful of streams, not a house full. Synology's ECC model, the DS925+, cannot hardware-transcode at all, so for Plex these two are the Synologys to buy.
Yes on current DSM. Per Synology's drive-compatibility FAQ (updated May 27, 2026), on the 2025 DiskStation Plus models under DSM 7.3, hard drives that are not on Synology's compatibility list can be used for new installations and storage pools, at the owner's discretion; drives on Synology's incompatibility list are refused, and Synology only guarantees full functionality with listed drives. M.2 NVMe SSDs in the DS425+ must be on Synology's list to create a cache or pool.
For file sharing, photo backup, sync and Plex, yes. For several Docker containers it is tight, and neither box is a VM host: the official maximum is 6GB (2GB onboard plus a 4GB module in the one memory slot), per Synology. If you want to self-host heavily, look at the QNAP TS-464 (to 16GB), the TerraMaster F4-424 (to 32GB) or Synology's DS925+ (32GB ECC, no hardware transcoding).
Using Synology's own figures and the US average residential rate of 18.44 cents per kWh, the DS225+ costs about $10 a year at its 6.08W hibernation draw and about $27 a year at its 16.98W access draw if it sat there 24/7; the DS425+ costs about $10 and $46 a year at 6.10W and 28.25W. Real use falls between the two. Synology measures with its own drives; your drives change the numbers.