Side-by-side specifications of the Synology RS2421+ and RS2825RP+, from official datasheets. Differences are highlighted.
| RS2421+ | RS2825RP+ | |
| CPU | AMD Ryzen V1500B | AMD Ryzen V1780B |
| Cores / threads | 4 cores | 4/8 |
| RAM (base) | 4 GB | 8 GB |
| RAM (max) | 32 GB | 32 GB |
| Drive bays | 12 | 16 |
| Expandable to | 24 | 28 |
| M.2 slots | 0 | 2 |
| Network | 4 x 1GbE RJ-45 | 2x1GbE + 1x10GbE |
| 10GbE | optional | yes |
| Max raw capacity | 24 drives | 560 TB |
| Hot-swap | yes | yes |
| Form factor | Rackmount 2U | 3U |
| Released | 2021 | 2025 |