Synology DS425+ NAS Review
Synology DS425+ Review – Should You Buy This NAS?
The Synology DS425+ is a 4-bay NAS system launched in mid-2025 as part of the company’s continued refresh of its Plus Series product line, replacing the DS423+. It is designed to serve home power users, creative professionals, and small business environments that require a balance of reliable storage, streamlined software integration, and modest multimedia capabilities. The unit retains a familiar chassis and architecture, featuring the Intel Celeron J4125 quad-core processor (2.0 GHz base, 2.7 GHz burst) with integrated graphics support, 2GB of soldered DDR4 memory (expandable up to 6GB with an additional 4GB Synology module), and two M.2 NVMe slots intended primarily for SSD caching using Synology-verified drives.
Alongside this hardware, the DS425+ runs DSM 7.2 and includes the full suite of Synology services, such as Active Backup, Surveillance Station, Virtual Machine Manager, Synology Drive, and Hybrid RAID (SHR) support. Network connectivity is handled by a single 2.5GbE and a 1GbE port, while two USB 3.2 Gen 1 ports enable external storage or UPS integration. Despite minimal hardware changes over its predecessor, the DS425+ demonstrates Synology’s continued focus on efficiency, low noise output, and energy-conscious operation—important factors for users planning to run a 24/7 NAS. However, these choices also reflect broader changes in Synology’s platform strategy that may not suit every user, especially those seeking higher flexibility or modern internal specifications.
6.6
DSM 7.2 Operating System: Offers a rich suite of first-party apps including Active Backup, Surveillance Station, Synology Drive, and Hyper Backup with strong cross-platform support.
Low Noise and Power Consumption: Quiet 92mm fan setup and efficient power usage (~28W under load) make it ideal for 24/7 operation in home or office environments.
Integrated Graphics (Intel UHD 600): Supports light Plex or Jellyfin hardware transcoding for 1080p media, a rare inclusion in Synology’s 2025 lineup.
Compact and Versatile Design: Small chassis with 4 SATA bays and 2 M.2 NVMe slots for cache acceleration, supporting RAID 5/6 and SHR.
Strong Security Posture: Includes 2FA, SSL, VPN tools, and a proactive PSIRT vulnerability disclosure program for ongoing protection.
Good Thermal Management: Maintains stable drive and system temperatures (~32–35°C) even under moderate load.
Broad Software Ecosystem: Additional apps like Synology Photos, Chat, Office, and Drive make it a multi-functional NAS beyond just storage.
Strict Drive Compatibility: Requires Synology-only HDDs and SSDs for full functionality; third-party drives trigger warnings or are blocked entirely.
Outdated CPU Platform: Uses a 2019-era Intel J4125 CPU, now underpowered compared to newer Intel N-series or AMD embedded chips.
Memory Upgrade Limitations: Comes with 2GB soldered RAM, upgradeable to only 6GB total, and officially supports Synology-branded memory only.
Limited Connectivity and I/O: No PCIe, eSATA, or SD card support; only one 2.5GbE and two 5Gbps USB ports—lagging behind competitors in 2025.
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Synology DS425+ NAS |
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DSM Software Ecosystem and Integration
One of the most compelling reasons to consider the DS425+ is its support for Synology’s DiskStation Manager (DSM), a mature and highly integrated NAS operating system. DSM 7.2, which comes preinstalled, offers a unified and consistent user experience with a wide range of built-in applications tailored for home users, remote workers, and small office setups. Core tools like Active Backup for Business allow centralized backup of entire operating systems, folders, and virtual machines, making the DS425+ useful as a bare-metal recovery or disaster recovery node. Hyper Backup enables encrypted, versioned backups to local, remote, or cloud destinations, while tools like Snapshot Replication provide rapid rollbacks and protection against ransomware.
Synology also offers sector-specific solutions through packages like Surveillance Station and Virtual Machine Manager, the former allowing support for up to 40 cameras (with up to 800FPS at 1080p H.264), and the latter providing basic VM hosting for Linux and lightweight Windows workloads. These tools are tightly optimized for the hardware, with low overhead and accessible browser-based management. Furthermore, the DS425+ supports Synology Hybrid RAID (SHR), giving users more flexibility when mixing drive capacities and minimizing unused storage space compared to traditional RAID models.
DSM extends beyond simple storage management by including companion apps like Synology Photos, Drive, and Chat, all of which are compatible with Windows, macOS, Android, and iOS. The DS425+ integrates these tools with centralized user management, group permissions, and support for LDAP and Active Directory.
For users who value reliability, Synology’s proactive security strategy—including its public security advisories, pen-testing initiatives, and in-house incident response—adds extra confidence to the long-term stability and safety of the system. In many cases, users report that the simplicity and polish of DSM is what keeps them loyal to the Synology platform, even when hardware specifications appear modest.
Strict Drive Compatibility and Locked Storage Expansion
One of the most significant limitations of the DS425+ is its strict enforcement of Synology-only drive compatibility, particularly for both 3.5″ HDDs and M.2 NVMe SSDs. As of mid-2025, this model only allows full functionality when paired with Synology-branded drives, such as the HAT5300 series for hard disks or SNV3410/3510 for SSDs.
If users attempt to install non-Synology drives—even widely used options like Seagate IronWolf or WD Red—the system will either block the drives entirely or present warnings and restrict key functionality, such as RAID rebuild, hot spare assignment, or expansion. This policy represents a significant departure from Synology’s historically broader compatibility stance and has become a source of ongoing controversy among users and reviewers alike.
From a practical standpoint, this limitation can result in higher upfront costs, reduced flexibility in sourcing drives, and long-term concerns about availability and vendor lock-in. For example, Synology’s high-capacity enterprise HDDs are often difficult to find in retail channels and may be priced at a premium compared to similar offerings from Seagate or Toshiba.
Users migrating from older Synology systems who want to reuse perfectly functional drives may find themselves unable to do so, as the new system won’t allow proper array recovery or expansion unless all drives meet the strict compatibility criteria. While this approach enables Synology to tightly optimize performance and reliability, it effectively turns the DS425+ into a semi-proprietary ecosystem where even core storage components are vendor-restricted.
This is particularly frustrating for experienced NAS users who expect to mix and match drives or who run environments where hardware recycling and drive lifecycle management are critical. The decision also impacts future-proofing: users who want to grow their arrays over time must now ensure drive stock alignment with Synology’s approved list, which may change over time or vary by region. Despite DSM’s strengths, this hard stance on compatibility significantly undermines one of the key selling points of NAS platforms—modularity—and could be a dealbreaker for value-conscious users or those with existing disk investments.
Low Noise and Power Efficiency for 24/7 Use
Another advantage of the DS425+ lies in its energy-efficient and acoustically quiet design, which makes it highly suitable for constant operation in homes, studios, or office environments where noise and heat are critical considerations. Based on extended testing, the system consumes just 28.25W under access load and drops to as low as 6.10W in HDD hibernation, making it one of the more economical NAS units in its class when measured over long-term 24/7 usage.
Even when populated with four 4TB hard drives and placed under sustained load, real-world power draw rarely exceeded 44W during high CPU utilization. This is further aided by the relatively low thermal output, with ambient casing temperatures measured around 32°C and drive bays stabilizing at just 35°C under load.
In terms of acoustic performance, the DS425+ is equipped with two 92mm fans, and noise testing shows the system remains quiet enough for close-proximity deployment. In idle mode with the fans on their lowest profile, it registers a sound level between 36 to 38 dB(A), which increases only moderately under load or at medium fan speed. Even when the system was manually set to full fan speed with high drive activity, noise output peaked at 53 dB(A)—still manageable for most non-silent workspaces. This operational profile makes the DS425+ appealing to users seeking a low-maintenance NAS that can be discreetly placed in a shared room, office, or AV rack without introducing unwanted distraction or thermal buildup.
This power and noise behavior also helps prolong component lifespan, particularly in warmer climates or enclosed cabinets, and supports use cases like 24/7 media server operation, offsite backups, or even small-scale CCTV archiving. Importantly, despite these low operating figures, the DS425+ still maintains stability and consistent throughput thanks to the efficiency of the J4125 processor and DSM’s power-aware service management. These characteristics, often underappreciated in specs alone, make it especially suitable for those who want reliable long-term uptime without high energy costs or acoustic interference.
Memory Limitations and Unorthodox Upgrade Path
The DS425+ comes with 2GB of DDR4 memory soldered directly to the motherboard, which is low by 2025 standards even for entry-level NAS devices. While it includes an additional memory slot that allows for the installation of a single 4GB module, the system officially supports a maximum of just 6GB of total RAM. This is an unusual and restrictive configuration, especially when many modern NAS devices now ship with 4GB or 8GB by default, and support 16GB or more—sometimes with dual-channel configurations for better performance. Synology’s strict validation policy also means that only their branded RAM (e.g. D4NESO-2666-4G) is fully supported, and installing third-party modules can trigger warnings in DSM or potentially void support coverage.
This memory ceiling becomes problematic when running DSM features that scale with RAM usage, such as Synology Drive, Snapshot Replication, Virtual Machine Manager, or Surveillance Station. As observed during testing, the DS425+ routinely used 27–38% of its available memory at idle, even without third-party packages installed. This is largely due to DSM’s intelligent memory caching system, which improves performance but leaves little headroom for user-defined workloads. Once additional services or multimedia indexing tasks are introduced, memory utilization climbs quickly, increasing the risk of slowdowns, swap usage, or outright service failure under peak demand.
For users who intend to deploy containers, host multiple camera feeds, or run even a small number of VMs, this limitation may lead to bottlenecks sooner than expected. It also makes the DS425+ a less viable choice for future expansion or multi-user environments. Unlike other NAS brands that allow full third-party upgrade freedom—or systems with dual RAM slots and broader capacity support—Synology’s enforced limitations here represent another example of the platform’s increasingly locked-down approach. For a system marketed to prosumers, the inability to exceed 6GB RAM comfortably is a notable technical and strategic constraint.
Integrated Graphics for Light Media Transcoding
Unlike many NAS units in this price tier, the DS425+ includes an Intel Celeron J4125 processor with integrated Intel UHD Graphics 600, which unlocks hardware-accelerated video decoding and transcoding in supported applications like Plex or Jellyfin. This makes the DS425+ one of the few Synology models in 2025 that still offers integrated GPU support out of the box, especially as newer Synology models with more recent CPUs have increasingly omitted integrated graphics. While the DS425+ is not intended to replace a dedicated media server, its GPU can significantly improve performance and efficiency for on-the-fly transcoding of formats like H.264 and H.265 (HEVC), particularly when streaming to remote clients with bandwidth constraints.
In real-world usage scenarios, this means the DS425+ can handle direct streaming and limited transcoding of 1080p content without overwhelming the CPU, provided the source formats are within the GPU’s supported codec list. During Plex testing, the DS425+ performed adequately with one or two 1080p transcodes running simultaneously, and was also able to manage basic 4K downscaling if the codec was natively supported by the hardware. For home users who have mixed devices—such as smart TVs, mobile devices, and tablets that vary in codec support—the presence of hardware transcoding offers improved flexibility without requiring as much manual conversion or format standardization of their media library.
Additionally, Synology’s native multimedia applications such as Surveillance Station and Synology Photos also benefit from GPU acceleration, helping speed up thumbnail generation, indexing, and playback, especially for high-resolution image and video collections. While raw CPU power in the DS425+ is modest by 2025 standards, the inclusion of integrated graphics helps balance out performance for lightweight graphical workloads and makes the system more viable as a general-purpose media hub. For users considering a NAS for Plex, family media streaming, or small business content previews, this capability adds meaningful value—especially since few modern Synology NAS devices still include Intel-based chips with iGPU support.
Outdated CPU Platform and Limited Performance Headroom
The DS425+ ships with the Intel Celeron J4125, a 4-core, 4-thread processor that was originally launched in late 2019. While it offers modest performance and includes integrated graphics, the J4125 is now significantly behind modern alternatives in both efficiency and raw compute power. Intel itself has discontinued the Celeron branding entirely, moving toward newer architectures like Alder Lake-N and Jasper Lake, which offer improved IPC (instructions per cycle), higher core/thread counts, and better thermal efficiency—all while retaining low power consumption. In comparison, the J4125’s aging 14nm Gemini Lake architecture struggles with heavier multitasking, especially when running services like virtual machines, surveillance workloads, or multiple Docker containers in parallel.
Synology has retained this CPU across several generations of its 2- and 4-bay Plus series models, which makes the DS425+ feel less like a generational upgrade and more like a lateral move. During performance testing, the unit handled DSM core tasks and multimedia indexing smoothly, but CPU load increased sharply under heavier tasks such as simultaneous Surveillance Station streams, Hyper Backup routines, or basic VM instances.

This limited headroom constrains the DS425+ to light-to-moderate workloads, and it can bottleneck more quickly than newer systems from other brands using more recent Intel N-series or AMD Ryzen Embedded CPUs. This is especially important as DSM continues to add new features that may increase background resource consumption over time.
Additionally, the CPU’s lack of support for modern instruction sets or features like AVX can limit compatibility with certain Docker containers or third-party applications that expect more recent hardware. While the DS425+ can serve well as a general-purpose file server or light media NAS, it’s not suited for users who anticipate growth into heavier mixed-use deployments. In a 2025 market where many similarly priced NAS units offer 6- or 8-core CPUs and PCIe Gen 3 or 4 support, the DS425+ feels constrained and unlikely to age well for users with evolving or expanding workloads.
Compact Form Factor with Versatile Storage Options
The DS425+ offers a space-efficient chassis design that houses four 3.5″/2.5″ SATA drive bays, along with two M.2 2280 NVMe SSD slots for caching. This provides a versatile platform for users who want flexible storage layouts without moving to a physically larger or more expensive rackmount or tower system.
The vertical orientation of the chassis, measuring just 166 x 199 x 223 mm, makes it easy to deploy the device in tight workspaces, shelving units, or beneath desks—ideal for small offices, home studios, or AV setups where space is at a premium. Despite its small footprint, the device retains full support for key RAID configurations including SHR, RAID 5/6/10, and JBOD, and offers hot-swappable access to the main drive bays for ease of maintenance.
The inclusion of two M.2 NVMe slots on the base of the unit allows users to improve performance through read/write caching without sacrificing primary drive bays. Although these M.2 slots are limited to Synology-verified SSDs and are not usable for storage pools, they can still offer significant boosts to random I/O performance in multi-user environments or when used with demanding workloads like Synology Drive or VM hosting. Combined with support for SSD TRIM and smart cache algorithms within DSM, the system can be tuned to optimize response times during high-access periods without introducing large amounts of memory overhead.
From a practical standpoint, this layout is beneficial for users managing multiple storage tiers, such as a mix of large-capacity HDDs for archiving and faster SSDs for active projects or virtual machines. Furthermore, the DS425+ supports volume expansion using larger capacity drives, RAID migration options (e.g. from Basic to RAID 5 or RAID 5 to RAID 6), and up to 32 internal volumes, giving users enough headroom for future scaling. These features, while standard in DSM, are fully supported in this chassis and make it easier to adapt the NAS as storage needs evolve—without the need to start from scratch or invest in a new enclosure.
Limited I/O and Underwhelming Connectivity for the Price
While the DS425+ introduces a 2.5GbE network port alongside a legacy 1GbE port, the rest of its I/O configuration is relatively limited and arguably outdated compared to competitors in its price range. The system includes just two USB 3.2 Gen 1 ports, both of which operate at 5Gbps rather than the more modern 10Gbps (Gen 2) speeds that are increasingly common in 2025. There is no SD card slot, no eSATA or PCIe expansion slot, and no HDMI output, all of which are features now appearing on rival NAS systems from QNAP, TerraMaster, and UGREEN—even at similar or lower price points. These omissions restrict how the device can be expanded or integrated into more complex workflows, such as direct-attached backup targets, external GPU support, or quick media ingestion.
The presence of only a single 2.5GbE port also imposes a bottleneck for users wanting to make full use of SSD caching or high-throughput RAID configurations. There is no support for link aggregation, as the 1GbE and 2.5GbE ports cannot be bonded in a meaningful way, and the system lacks support for 5GbE or 10GbE—either onboard or via expansion. In scenarios where large video files, virtual machine images, or multiple users are simultaneously accessing data, the NAS may become network-bound more quickly than other models with multi-GbE or SFP+ connectivity.
Furthermore, while DSM offers support for USB peripherals such as external drives and UPS devices, the limited port count and bandwidth mean there is little headroom for simultaneous external expansions, and the brand limits the support of USB peripherals for security reasons. For example, attaching both an external drive and a USB-connected UPS may require unplugging one to rotate in another device. This may not impact casual home users, but for power users managing workflows like video editing, offsite rotation backups, or multi-location file sync, this level of I/O flexibility feels dated. When factoring in the DS425+’s pricing, which places it near many NAS models with more expansive I/O, this minimalism can be a significant drawback.
Strong Security Framework and Proactive Vulnerability Management
The DS425+ benefits from Synology’s broader emphasis on security, offering a robust framework for data protection, secure remote access, and proactive threat mitigation. DSM includes built-in tools such as firewall rules, auto-blocking of suspicious IPs, HTTPS configuration, and native integration with Let’s Encrypt for SSL certificates. Two-factor authentication (2FA) can be enforced per user or globally, and built-in VPN server options (including OpenVPN and L2TP/IPSec) provide secure tunnels for remote workers or offsite access. For businesses or power users hosting sensitive data, the inclusion of AES-NI hardware encryption ensures efficient at-rest protection without drastically impacting system performance.
What sets Synology apart is its ongoing commitment to security research and response. The company operates a public-facing Product Security Incident Response Team (PSIRT) and regularly updates a detailed security advisory page disclosing vulnerabilities and their mitigations. Synology also participates in Pwn2Own, a white-hat hacking competition, and runs internal bug bounty programs to uncover and patch exploits before they are discovered in the wild. This culture of transparency and preemptive action is especially valuable as NAS devices become more frequently targeted by malware and ransomware threats, particularly those exposed to the internet or used in hybrid cloud workflows.
Additionally, many DSM apps include granular permission management, audit logs, and user-based access rules, giving administrators tight control over file shares, backup targets, and service access. Synology’s Hybrid Share and Cloud Sync tools support end-to-end encryption and offer options to decouple cloud storage keys from the local system, further strengthening data sovereignty. For users concerned with long-term viability and platform trust, Synology’s structured and well-documented security practices help the DS425+ stand out against competitors that may offer more hardware but less attention to software and infrastructure hardening. This makes it a viable choice for users prioritizing data safety in either personal or professional contexts.
Questionable Long-Term Value Amid Shifting Synology Strategy
Another concern with the DS425+ is its position within Synology’s evolving product strategy, which raises questions about long-term support and ecosystem focus. Synology has recently been expanding its BeeStation and BeeStation Plus lines—pre-populated, user-friendly NAS solutions that share similar hardware (in some cases, the same J4125 CPU), but are bundled with drives and offer a simplified DSM variant tailored for general consumers. These systems, while more limited in scope, are marketed as turnkey alternatives with lower pricing and fewer user-configurable components. The DS425+, by contrast, sits awkwardly between Synology’s increasingly restrictive hardware requirements and the emerging shift toward closed, fully managed platforms.
This change in trajectory creates uncertainty for prospective buyers looking for a long-term investment. If Synology continues prioritizing its proprietary hardware and software pairings, users who prefer modularity, drive freedom, or advanced customization may find themselves increasingly constrained. As already noted, the DS425+ enforces tight compatibility rules, limits memory expansion, and restricts NVMe usage to caching only. At the same time, Synology is streamlining its portfolio around devices with even stricter limitations but more mass-market appeal. This raises the possibility that traditional “Plus” models like the DS425+ may be sidelined or see fewer feature updates in future DSM releases, as Synology shifts development toward more controlled environments.
From a cost perspective, the DS425+ is priced around $519, placing it uncomfortably close to more powerful third-party NAS systems that offer better CPUs, more RAM, and greater I/O flexibility. Competing brands frequently offer 4-bay systems with modern N-series Intel processors or embedded AMD chips, 8GB+ of memory, and faster networking, often for the same or lower price. As a result, the DS425+ risks being outclassed not only by its competition, but by Synology’s own growing lineup of prepackaged solutions. Users investing in the DS425+ today may find themselves limited not just by current specs, but by an ecosystem slowly drifting away from the prosumer and enthusiast segment this model was originally meant to serve.
Synology DS425+ NAS Review – Conclusion and Verdict
The Synology DS425+ presents a mixed proposition in 2025. On one hand, it remains a competent 4-bay NAS solution for users prioritizing software integration, low power operation, and quiet, reliable 24/7 usage. Its support for DSM 7.2 and the full suite of Synology applications—ranging from Active Backup to Surveillance Station and Synology Drive—makes it a strong turnkey platform for general-purpose storage, backup, and multimedia needs. Integrated graphics give it an edge in light media streaming scenarios, and its support for M.2 NVMe caching allows for performance optimization without occupying drive bays. It’s a well-built device that continues to “just work,” particularly in home and small office setups where reliability, simplicity, and refined software matter more than raw horsepower.
However, these strengths are increasingly offset by hardware limitations and Synology’s increasingly restrictive ecosystem. The soldered 2GB of RAM, locked 6GB memory ceiling, outdated CPU, limited I/O, and especially the enforced use of Synology-only drives all hinder flexibility and long-term value. When compared to similarly priced alternatives from competing NAS vendors—many of which offer newer processors, faster ports, and full hardware freedom—the DS425+ can feel constrained and overpriced. In addition, Synology’s expanding focus on pre-populated BeeStation devices suggests a possible shift away from traditional DIY-friendly models like this one. For users who are already invested in the Synology ecosystem or who value DSM above all else, the DS425+ may still be a worthwhile buy. But for those seeking hardware scalability, third-party compatibility, or better price-to-performance, it may be worth considering other options or waiting to see how Synology’s roadmap evolves.
Synology DS425+ NAS |
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Amazon in Your Region for the Synology DS425+ NAS @ $519 |
B&H for the Synology DS425+ NAS @ $519.99 |
Synology DS425+ NAS Pros | Synology DS425+ NAS Cons |
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