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The WD My Cloud EX4100 is a four-bay network-attached storage (NAS) device whose appeal today depends less on its original feature list than on its software state. WD lists OS 5 firmware 5.33.102, dated March 24, 2026, and a support timeline through December 2027. An EX4100 still running OS 3 is a different proposition: WD ended OS 3 support on April 15, 2022, including security updates and remote access.
This is a specifications-and-support review, not a hands-on test. WD’s documentation establishes the hardware and listed features, but no independent benchmark, current price, or current retail availability is established here.
What is the WD My Cloud EX4100?
The EX4100 is a four-bay NAS for storing files on a local network and, where software and configuration permit, accessing them remotely. WD introduced the model in 2015. Its documented hardware includes a 1.6 GHz dual-core Marvell ARMADA 388 processor and 2 GB of DDR3 memory; these are manufacturer specifications, not measured performance results. WD’s February 2015 EX4100 data sheet describes the device and its original capabilities.
Ports and drive bays
- Four tray-less, hot-swap-capable 3.5-inch drive bays.
- Two Gigabit Ethernet ports.
- Two rear USB 3.0 expansion ports and one front USB 3.0 direct-copy port.
- Two power inlets.
Hot-swap capability describes the bay design; it is not a substitute for backups or a guarantee that every drive replacement is safe in every configuration. Check the device’s status and instructions before changing a drive.
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- Centralized, whole-home storage
- Mobile and remote web access, Backs up PC and Mac computers
- Photo and video backup for smartphones and tablets, Operating System - Windows/Mac
- Sync software to keep content up-to-date across all your computers and creates a common place for friends and family to share photos
- Compatible with Windows 10, Windows 8, Windows 7, Mac OS X El Capitan, Yosemite, Mavericks, or Mountain Lion operating systems and requires, DLNA/UPnP devices for streaming and a router with Internet connection
What RAID and network features does it offer?
WD’s data sheet lists JBOD, spanning, RAID 0, 1, 5 and 10, as well as hot-spare support in four-disk mode. The right arrangement depends on how much capacity, redundancy and recovery complexity you can accept. RAID is not a backup: it does not protect against accidental deletion, theft, all hardware failures, or damage to the NAS itself.
The two Ethernet ports are specified for link aggregation and failover. WD also lists SMBv3, AFP, NFSv3, FTP/SFTP, WebDAV and iSCSI, plus Active Directory support and 256-bit AES volume encryption. These are historical manufacturer-listed capabilities, not assurances that every protocol or integration is enabled, secure, supported, or appropriate on a particular unit today. Review the actual firmware and configuration before exposing services to a network.
Rank #2
- Input voltage range of AC 100-240V allows for use in different countries and regions. Output current of DC 19V 4.74A for efficient power conversion.
- Compatible with WD 24TB 32TB My Cloud EX4100 Expert Series 4-Bay Network Attached Storage
- Compatible with WD WDBWZE0240KBK-NESN / WD WDBWZE0320KBK-NESN
- Compatible with DNS-343 4-Bay Storage Enclosure; A OPEN XCcube aopen MZ915-M Computer
- Compatible with MSI GE72 APACHE-235 i7-5700HQ
Which firmware and operating system does the EX4100 support?
WD’s EX4100 support page lists My Cloud OS 5 firmware 5.33.102 dated March 24, 2026. It also lists OS 3 firmware 2.42.115 dated January 18, 2022. These entries describe available downloads, not what is installed on an individual NAS. Check WD’s EX4100 support page and verify the operating system and firmware shown by your own device before following an update path.
WD states that OS 3 firmware 2.42.115 must be installed before updating to OS 5, and warns that some OS 3 features and apps will not be available after upgrading. Do not assume an OS 5 update is a feature-preserving or universally reversible change; consult WD’s current instructions and account for the loss of any feature you rely on.
Rank #3
- [Power Specification]: Input Voltage: 100~240V Input Frequency: 50~60HZ output Voltage: 19V
- [Compatible with]: My Cloud Pro Series PR4100 WDBNFA0000NBK- NESN WDBNFA0080KBK- NESN WDBNFA0160KBK- NESN WDBNFA0240KBK- NESN WDBNFA0320KBK- NESN WDBNFA0400KBK- NESN WDBNFA0560KBK- NESN WDBNFA0640KBK- NESN WDBNFA0720KBK- NESN 0TB 8TB 16TB 24TB 32TB 40TB 56TB 64TB 72TB Network Attached Storage
- [Compatible with]: My Cloud Expert Series EX4100 WDBWZE0000NBK- NESN WDBWZE0080KBK- NESN WDBWZE0160KBK- NESN WDBWZE0240KBK- NESN WDBWZE0320KBK- NESN WDBWZE0400KBK- NESN WDBWZE0560KBK- NESN 0TB 8TB 16TB 24TB 32TB 40TB 56TB Network Attached Storage
- [Safety]: Tested, Approved and Certified by UL. Short circuit protection, Over temperature protection, and Over voltage protection.PCB & Cover is manufactured with Fireproofing materials.Use temperature protection NTC. Use insulation paper to isolate electrodes. Use fire protection glue paper and silica gel for safety features, it's security when notebook PC computer is working.
- [Fast and Efficient Charging]:This charger delivers a rapid and efficient charge to your devices, ensuring minimal downtime. Whether you're working on an important project, streaming your favorite content, or simply browsing the web, this charger that sold by PowerHOOD provides a reliable power source to keep you going.
OS 3 is no longer supported
WD ended My Cloud OS 3 support on April 15, 2022. WD says affected devices no longer receive remote access, security updates, or technical support. Its notice recommends backing up content, disabling remote access, disconnecting the device from the internet, and setting a strong, unique local device password. Read WD’s OS 3 end-of-support notice if your EX4100 is still running OS 3. The loss of security updates and the recommended internet disconnection make OS 3 a material security limitation, not merely an old interface.
WD’s published support timeline
WD’s product lifecycle policy lists the EX4100 from February 2015 through December 2027. This is WD’s published support timeline, not a guarantee that any particular service will remain available after that date. See WD’s product lifecycle policy for the manufacturer’s current listing.
Rank #4
- Product Type: Replacement AC Adapter
- Input: 100-240V 50/60Hz Output: 19V
- Certification: ETL Listed, with FCC,CE,ROHS certified
- Compatibility: Western Digital WD My Cloud Pro Series PR4100/ My Cloud Expert Series EX4100 Network Attached Storage 0TB 8TB 16TB 24TB NAS Enclosure Power Supply Charger; My Cloud Pro Series PR4100 WDBNFA0000NBK- NESN WDBNFA0080KBK- NESN WDBNFA0160KBK- NESN WDBNFA0240KBK- NESN WDBNFA0320KBK- NESN WDBNFA0400KBK- NESN WDBNFA0560KBK- NESN WDBNFA0640KBK- NESN WDBNFA0720KBK- NESN 0TB 8TB 16TB 24TB 32TB 40TB 56TB 64TB 72TB Network Attached Storage
- Protection: OVP / OCP / SCP
What backup and media features are documented?
WD’s original feature sheet lists local or remote backup to another My Cloud Expert Series device, backup to attached USB storage, Amazon S3 and ElephantDrive, WD SmartWare Pro, and Apple Time Machine support. It also lists Twonky, DLNA 1.5 and an iTunes server. These are historical feature claims from WD’s documentation; they do not establish that each app, cloud service, integration, or remote function remains available today. Confirm current availability and compatibility before relying on one.
The EX4100 manual describes checking and manually installing firmware. Use the manual and the device-specific support page for the applicable procedure rather than assuming an update path based on a different My Cloud model. WD’s EX4100 user manual is the model-specific reference.
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It may suit an owner who already has an EX4100, wants a four-bay local storage device, and can verify that its current firmware and required functions meet their needs. The published OS 5 firmware and lifecycle listing through December 2027 are relevant signals, but they do not prove a particular device’s condition, present-day app availability, or post-2027 support.
For a new purchase, the evidence here is not enough to recommend the EX4100 over current NAS models. There is no independent performance testing, current price or availability information, current drive-compatibility evidence, or researched comparison with alternatives. Before committing, check firmware and support status, drive compatibility, usable capacity under the intended RAID arrangement, backup and remote-access requirements, noise and power, warranty, and the total cost including drives. No model-specific drive recommendation is established here.
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