Side-by-side specifications of the Synology RS2421+ and RS2423+, from official datasheets. Differences are highlighted.
| RS2421+ | RS2423+ | |
| CPU | AMD Ryzen V1500B | AMD Ryzen V1780B |
| Cores / threads | 4 cores | 4/8 |
| RAM (base) | 4 GB | 8 GB DDR4 ECC UDIMM |
| RAM (max) | 32 GB | 32 GB |
| Drive bays | 12 | 12 |
| Expandable to | 24 | 24 |
| M.2 slots | 0 | 0 |
| Network | 4 x 1GbE RJ-45 | 2x 1GbE, 1x 10GbE |
| 10GbE | optional | yes |
| Max raw capacity | 24 drives | 432 TB |
| Hot-swap | yes | yes |
| Form factor | Rackmount 2U | 2U |
| Released | 2021 | 2025 |
The RS2423+ is the better pick if you want newer hardware: it uses a faster Ryzen V1780B CPU and supports up to 32GB RAM, versus the RS2421+’s older Ryzen V1500B and 32GB max as well, but the RS2423+ also adds built-in dual 1GbE plus optional 10GbE via a PCIe card and supports NVMe M.2 cache. Both are 12-bay 2U units with expansion support, but the RS2423+ is the clearer upgrade for performance and future-proofing.