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 / 8 threads | 4 cores / 8 threads |
| RAM (base) | 4 GB DDR4 ECC UDIMM | 8 GB DDR4 ECC UDIMM |
| RAM (max) | 32 GB | 32 GB |
| Drive bays | 12 | 16 |
| Expandable to | 24 total with 1 RX1217/RX1217RP | 12 (up to 28 total with RX1225RP) |
| M.2 slots | 0 internal; via PCIe adapter | 0 (via adapter card) |
| Network | 4 x 1GbE RJ-45 | 2× 1GbE RJ-45, 1× 10GbE RJ-45 |
| 10GbE | optional | yes |
| Max raw capacity | 108 TB single volume; 24 bays with expansion | 560 TB raw |
| Hot-swap | yes | yes |
| Form factor | Rackmount 2U | 3U rackmount |
| Released | 2021 | 2025 |
| Power consumption | — | 134.48 W / 50.81 W |
| DSM at launch | — | — |