Excellent price-performance balance.
Good value for mid-range needs.
Versatility and advanced features.
👍 What we like
- ✓Reliable and secure offsite backup
- ✓High transfer performance for large data volumes
- ✓Versatile functionality with diverse operation options
👎 What to watch
- ✕Higher initial cost compared to alternative solutions
- ✕Technical complexity for installation and maintenance
- ✕Requires a stable internet connection for offsite synchronization
🏆 Our picks
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Asustor Flashstor 6 FS6706T
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📑 Contents ▾
A NAS (Network Attached Storage) is an essential tool for ensuring offsite data backup in 2026. Installed at a friend’s place, it offers protection against local data loss risks such as natural disasters or thefts. High-end models like the Synology DS423+, QNAP TS-673A, and Asustor Flashstor 6 FS6706T are particularly well-suited for this mission, offering optimal performance, large storage capacity, and robust technical support. This buying guide will help you choose the best NAS for your situation by detailing technical specifications, key features, and budget considerations.
Why this choice matters
Using an offsite NAS has become a necessity for personal and professional data backup in 2026. The focus on cybersecurity and protection against internal and external threats has led to the emergence of more sophisticated and versatile models. High-end NAS devices like the Synology DS423+, QNAP TS-673A, and Asustor Flashstor 6 FS6706T come with advanced RAID support, allowing data replication across multiple disks. This feature ensures protection against hardware failures and guarantees continuous access to essential information in case of local issues. Additionally, these devices offer automated cloud backup options, simplifying offsite data management without manual intervention.
Buying criteria
To choose the best NAS for an offsite installation at a friend’s place in 2026, we compared their spec sheets on three key criteria: storage capacity, performance, and data security. Storage capacity is crucial to ensure that the NAS can accommodate all data to be backed up, including future updates or additions. Performance determines the speed of data transfer to and from the device, influencing how often it needs to be used to maintain a secure offsite copy. Finally, data security is a vital aspect that ensures stored information is protected against unauthorized access or cyber threats.
We did not test these devices: the comparison relies on their manufacturer spec sheets (processor, memory, bays, network, USB ports). Real-world speeds depend on the drives, the local network and the Internet link between the two sites; we do not quote any.
Presentation of the 3 recommended products
1. Synology DS423+
The Synology DS423+ is a four-bay NAS suited to offsite backup. According to its spec sheet, it has an Intel Celeron J4125, 2 GB of DDR4 expandable to 6 GB, four 3.5”/2.5” SATA bays, two M.2 NVMe slots, two 1GbE ports and two USB 3.2 Gen 1 ports. Capacity depends on the installed drives.
2. QNAP TS-673A
The QNAP TS-673A is a six-bay NAS. According to its spec sheet, it has an AMD Ryzen Embedded V1500B quad-core at 2.2 GHz, 8 GB of DDR4 expandable to 64 GB, six 3.5” SATA bays, two 2.5GbE ports (5GbE and 10GbE optional via a PCIe card), two PCIe Gen3 x4 slots, three USB 3.2 Gen 2 Type-A ports and one USB 3.2 Gen 1 Type-C port. It has no integrated GPU (optional via a PCIe card): no hardware transcoding out of the box.
3. Asustor Flashstor 6 FS6706T
The Asustor Flashstor 6 FS6706T is an all-SSD NAS: according to its spec sheet, it takes six M.2 NVMe SSDs (no 3.5” drive), with an Intel Celeron N5105, 4 GB of DDR4, two 2.5GbE ports, two USB 3.2 Gen 2 ports and an HDMI 2.0b output. Capacity depends on the installed SSDs.
Comparison table
| Model | Processor (spec sheet) | Drive slots (spec sheet) | Network (spec sheet) | Price |
|---|---|---|---|---|
| Synology DS423+ | Intel Celeron J4125 | 4 x 3.5”/2.5” SATA bays + 2 M.2 NVMe | 2 x 1GbE | see live price |
| QNAP TS-673A | AMD Ryzen Embedded V1500B | 6 x 3.5” SATA bays | 2 x 2.5GbE | see live price |
| Asustor Flashstor 6 FS6706T | Intel Celeron N5105 | 6 M.2 NVMe | 2 x 2.5GbE | see live price |
Specifications: manufacturer spec sheets (Synology, QNAP, Asustor). Price: see the live price, it varies with the market.
Use cases
The Synology DS423+ is particularly well-suited for users seeking a reliable solution with good value. Its ease of use (DSM) makes it an ideal choice for small businesses or families looking to perform regular offsite backups.
The QNAP TS-673A is the preferred option for those needing more versatility and advanced features. Its six bays and two PCIe slots (10GbE networking, SSDs) suit large media collections that need protecting, as long as you do not count on hardware transcoding: it has no integrated GPU.
The Asustor Flashstor 6 FS6706T is the best choice for those looking for a balance between versatility and performance. Its all-SSD M.2 format suits a more modest data volume; capacity depends on the number and size of the installed SSDs.
Pitfalls to avoid
One of the most common pitfalls when choosing an offsite backup NAS is overlooking maintenance costs and energy consumption. For example, the QNAP TS-673A spec sheet lists 21.9 W with drives asleep and 45.9 W in typical operation with all bays populated: over a year, the difference shows on the bill. Additionally, it’s important to verify if the device supports a suitable RAID configuration to ensure data protection against hardware failures.
Another frequent mistake is neglecting the need for a stable and secure internet connection for offsite synchronization. Without this connection, the NAS might not be able to perform scheduled backups automatically.
Verdict
In conclusion, the Synology DS423+ is our top recommendation for its simplicity (DSM) and its four bays. The QNAP TS-673A offers a good balance for users seeking more versatility, while the Asustor Flashstor 6 FS6706T is the best option for those who prefer an all-SSD format. For a complete list of recommended self-hosting hardware in 2026, visit our page /materiel-recommande/