Replacement for RS4021xs: Drop-In Alternatives We Stock
Looking for a replacement for the RS4021xs (Synology Rs4021Xs+ Rackstation 16-Bay Rackmount Nas Server)? Pro Disk Network ships drop-in replacements and equivalent modern parts from US inventory. Every alternate below is in-stock today with same-day shipping for orders placed before 2pm ET. If your unit is still under warranty, contact our engineering team — we offer cross-shipping for B2B customers on Net 30 terms.
About the RS4021xs
| SKU | RS4021xs |
|---|---|
| Product | Synology Rs4021Xs+ Rackstation 16-Bay Rackmount Nas Server |
| Current price | $11,804.49 |
| Stock status | In Stock |
| Detail page | View RS4021xs › |
Drop-in replacements for RS4021xs
Each part below is currently in our US warehouse, ships same-day for orders before 2pm ET, and includes our 90-day warranty. SKUs link to the full product page with photos, datasheets and B2B quote form.
SA3400 Synology SA3400 Highly scalable NAS equipped with an 8-core CPU and 16GB ECC RDIMM memory(Highly scalable NAS meeting extensive data storage needs)
SKU: SA3400
Price: $18,829.47
TS-873U-RP-16G-US QNAP TS-873U-RP-16G-US AMD R-Series RX-421ND 2.1GHz/ 16GB DDR4/ 6GbE/ 8SATA3/ USB3.0/ 8-Bay 2U Rackmount NAS for SMB
SKU: TS-873U-RP-16G-US
Price: $4,545.66
TS-1273U-RP-16G-US QNAP TS-1273U-RP-16G-US AMD R-Series RX-421ND 2.1GHz/ 16GB DDR4/ 6GbE/ 12SATA3/ USB3.0/ 12-Bay 2U Rackmount NAS for SMB
SKU: TS-1273U-RP-16G-US
Price: $5,333.86
TVS-1672XU-RP-I3-8G-US QNAP TVS-1672XU-RP-I3-8G-US Intel Core i3-8100 3.6GHz/ 8GB DDR4/ 4GbE/ 16SATA3/ USB3.1/ 16-Bay 3U Rackmount NAS for SMB
SKU: TVS-1672XU-RP-I3-8G-US
Price: $5,528.89
REXP-1620U-RP-US QNAP REXP-1620U-RP-US SAS/SATA/SSD 16-Bay 3U Rackmount RAID Expansion Enclosure for QNAP NAS
SKU: REXP-1620U-RP-US
Price: $6,019.50
EJ1600-V2-US QNAP EJ1600-V2-US SAS 12Gbps 16-Bay 3U Rackmount RAID Expansion Enclosure for QNAP NAS
SKU: EJ1600-V2-US
Price: $6,926.32
TES-1885U-D1521-16GR-US QNAP TES-1885U-D1521-16GR-US Intel Xeon Processor D-1521 2.4GHz/ 16GB RAM/ 6GbE/ 18SATA3/ 18-Bay 2U Rackmount NAS for Enterprise
SKU: TES-1885U-D1521-16GR-US
Price: $8,971.22
TS-1683XU-RP-E2124-16G-US QNAP TS-1683XU-RP-E2124-16G-US Intel Xeon E-2124 3.3GHz/ 16GB DDR4/ 6GbE/ 16SATA/ USB3.1/ 16-Bay 3U Rackmount NAS for Enterprise
SKU: TS-1683XU-RP-E2124-16G-US
Price: $9,526.49
How we pick replacements
Every recommendation above was selected using these criteria:
- Drop-in compatibility — same form factor (2.5"/3.5", PCIe slot, SFP port, etc.), so it fits the original chassis without modification
- Equivalent or better performance — matched on RPM/IOPS/speed/throughput, never downgraded
- Same-brand-preferred — we list the OEM-equivalent first when available, then trusted aftermarket
- Warranty coverage — 90-day Pro Disk warranty on every part, with 1-year option for B2B
- In stock today — never recommend a part that is on backorder
Need help confirming compatibility?
Our engineers validate every replacement against your specific server, switch, or chassis model before shipment. Email sales@prodisknetwork.com with your platform model (e.g., Dell PowerEdge R740, HP DL380 Gen10, Cisco Catalyst 9300) and we will confirm the exact part number that drops into your hardware.