Especificaciones de los Synology RS3621xs+ y RS4021xs+ en paralelo, de las fichas técnicas oficiales. Las diferencias están resaltadas.
| RS3621xs+ | RS4021xs+ | |
| CPU | Intel Xeon D-1541 | Intel Xeon D-1541 |
| Núcleos / hilos | 8 cores / 16 threads | 8 cores / 16 threads |
| RAM (base) | 8 GB DDR4 ECC UDIMM | 16 GB DDR4 ECC UDIMM |
| RAM (máx.) | 64 GB | 64 GB |
| Bahías | 12 | 16 |
| Ampliable a | 36 | 40 (with 2× RX1217/RX1217RP) |
| Ranuras M.2 | 0 (via PCIe adapter cards) | Optional via PCIe adapter cards |
| Red | 4×1GbE RJ-45, 2×10GbE RJ-45 | 4× 1GbE RJ-45; 2× 10GbE RJ-45 |
| 10GbE | yes | yes |
| Capacidad bruta máx. | 1 PB single volume | 1 PB single volume |
| Intercambio en caliente | yes | yes |
| Formato | 2U rackmount | 3U rackmount |
| Lanzamiento | 2021 | 2021 |
| Consumo | — | 145.79 W / 62.68 W |
| DSM de lanzamiento | — | — |