The shares have vanished, the volume says crashed, or the box answers on the network but hands you nothing. A NAS in this state is usually still holding every byte you are worried about — and the menu it is showing you contains at least one button that will change that permanently.
Before anything else, separate two problems that feel identical from a laptop. In the network version, the data is fine and the plumbing is not: an SMB version disabled by a Windows update, expired credentials, a changed IP, a router that renumbered the network. The unit’s own admin page still loads, the volume still reports healthy, and nothing is at risk. Reconnect and carry on.
In the storage version, the box is up and the data is not. Synology says Volume Crashed or Degraded; QNAP reports the pool unmounted or the volume inactive; a WD My Cloud sits blinking and shows no shares at all. The admin page usually still works — which is exactly what makes this dangerous, because it offers you a tidy row of buttons at the precise moment when pressing one costs you the array.
The most common cause by far is a single failing disk taking a redundant volume down with it. Synology Hybrid RAID, RAID 1 and RAID 5 all tolerate one dead member — but they tolerate it degraded, and a NAS that has been quietly degraded for eight months has been living on the last life it had. When the second disk stumbles, or when a rebuild is attempted and meets an unreadable sector, the volume drops out entirely. That is the RAID 5 rebuild problem arriving in a domestic cabinet.
The next most common is file-system damage rather than disk death: btrfs or ext4 metadata corrupted by a power cut mid-write, or by a firmware update that rebooted the unit while the volume was busy. The disks are all healthy, the array is intact, and the file system on top of it has lost its bearings. And then there is the deletion case — a share removed, a snapshot policy that never ran, a sync that propagated the mistake — where the hardware never failed at all. All three arrive at your screen looking exactly the same.
Every NAS interface offers to help, and its offers are written for a healthy machine. Repair Volume, Rebuild and Resync all begin writing across the remaining disks — the ones carrying the only copy of your data — and a rebuild that fails halfway leaves a mess that is far harder to unpick than the original fault. Create Volume and Initialise are worse still: they lay a fresh, empty structure over the top of everything, and no support-forum incantation brings that back.
Two more traps, both well-intentioned. Pulling the disks out and testing them one at a time in a USB dock destroys the one thing recovery depends on — the order the members sat in — unless you have labelled them by bay first. And factory-resetting the unit to “start clean” wipes the configuration that records how the array was assembled. If the volume is already down, the correct next action is not a button. It is the power switch: a Hamilton Synology came in exactly like this and went home whole, precisely because nobody pressed repair.
Recovery from a NAS never touches the original disks in anger. Every member is imaged individually on hardware that only reads; the array is then reconstructed virtually from those images — stripe order, parity rotation, SHR’s nested layout, btrfs metadata and all — and your shares are extracted from the rebuilt volume. Nothing is written back to the drives you sent, which is why a failed rebuild upstream is inconvenient rather than fatal, and why a My Cloud whose own rebuild had already failed could still be recovered in full.
Sending it is simple, and this is the one device class where the whole unit is welcome: post the NAS as it stands, or take the drives out and label them by bay — both work, an unlabelled pile is the only version that costs time. Everything is done in-house and nothing leaves the UK. NAS recovery starts from £500 + VAT with the diagnostic free, the figure fixed in writing before any work, and no fee on most jobs unless the data comes back.
The data is usually still there — right up until a rebuild writes over it. Shut the unit down, label the drives if you remove them, and let the free assessment tell you what is actually recoverable. NAS and RAID work from £500 + VAT, fixed in writing first.