Side-by-side specifications of the Synology RS2421RP+ and RS2821RP+, from official datasheets. Differences are highlighted.
| RS2421RP+ | RS2821RP+ | |
| CPU | AMD Ryzen V1500B | AMD Ryzen V1500B |
| Cores / threads | 4-core/4-thread | 4 |
| RAM (base) | 4 GB | 4 GB |
| RAM (max) | 32 GB | 32 GB |
| Drive bays | 12 | 16 |
| Expandable to | 24 | 28 |
| M.2 slots | optional via adapter | 2 |
| Network | 4 x 1GbE RJ-45 | 4 x 1GbE RJ-45 |
| 10GbE | optional | optional |
| Max raw capacity | 108 TB per volume | 108 TB |
| Hot-swap | yes | yes |
| Form factor | Rackmount 2U | 3U rackmount |
| Released | 2021 | 2021 |