A Synology NAS that supports Time Machine over SMB can serve as a macOS Time Machine backup destination, replacing Apple's discontinued Time Capsule and providing a more flexible, storage-expandable backup target for Mac users. DSM natively supports the Time Machine protocol over SMB (and legacy AFP), so your Mac can back up automatically to the NAS over your local network just like it would to a Time Capsule. Hourly incremental backups, full system recovery capability, and no cloud involved.
In short: Create a dedicated shared folder on the NAS, enable it as a Time Machine target in DSM File Services settings, add a quota to cap how much space Time Machine uses, then select the NAS share in macOS System Preferences > Time Machine. Use SMB (not AFP) for modern macOS versions (Catalina and later). Time Machine will consume all available space if you don't cap it.
SMB vs AFP: Which Protocol to Use
Time Machine has used SMB as its default protocol since macOS Sierra 10.12. Apple does not recommend AFP for NAS backups and says AFP support will end in macOS 27. DSM still supports AFP for older Macs, but use SMB for any Mac running macOS Catalina (10.15) or later. SMB is the protocol Apple and Synology currently recommend for Time Machine backups to a NAS.
AFP is still available in DSM via Control Panel > File Services > AFP. Enable it only if you're running a Mac on macOS Mojave or earlier. For everything 2021 and newer, ignore AFP and configure Time Machine via SMB.
Step 1. Create a Dedicated Shared Folder for Time Machine
Create a separate shared folder specifically for Time Machine. Using a dedicated folder makes it easy to monitor storage usage, set quotas, and manage permissions without affecting your other NAS data.
In DSM, open Control Panel > Shared Folder > Create. Name it something descriptive like TimeMachine or mac-backup. Select the volume with the most free space. Leave encryption off (Synology does not recommend encrypted shared folders as Time Machine destinations; use Time Machine's backup-encryption option instead). Click Next through the permissions step. You'll configure permissions shortly.
After creating the folder, go to Control Panel > Shared Folder > select TimeMachine > Edit > Permissions. Add the user account that your Mac will use to authenticate. The account needs Read/Write permission. If multiple Macs will back up to the same NAS, you can either use a single shared account or create separate DSM user accounts per Mac. Separate accounts make per-Mac quota management easier.
Step 2. Enable Time Machine Support on the Shared Folder
In Control Panel, go to File Services > SMB. Confirm SMB is enabled (it should be by default). Then go to the Advanced tab and scroll down to Time Machine. Under Control Panel > File Services > Advanced > Bonjour, enable Bonjour service discovery and Bonjour Time Machine broadcast via SMB, then click Set Time Machine Folders and select the shared folder. Save.
This registers the share as a Time Machine-compatible destination that macOS can discover via mDNS (Bonjour). On your local network, it will appear in the macOS Time Machine disk selection list without any manual configuration on the Mac side.
Storage quota (critical): Before connecting the Mac, set a quota on the TimeMachine folder to prevent Time Machine from filling your entire volume. In Control Panel > Shared Folder > TimeMachine > Edit, there's a Quota tab. Set a size limit. A good rule of thumb is 2-3× the size of your Mac's internal storage. For a Mac with a 1TB SSD, allow 2TB on the NAS. Time Machine keeps hourly snapshots for 24 hours, daily for a month, and weekly until the disk is full. More space means longer backup history retained.
Step 3. Connect macOS to the NAS Time Machine Share
On the Mac, open System Settings (macOS Ventura+) or System Preferences (Monterey and earlier). Go to General > Time Machine (Ventura+) or directly to Time Machine (older macOS).
Click Add Backup Disk (or Select Disk on older versions). The NAS should appear in the list. It shows up as the Time Machine share you enabled. If it doesn't appear:
- Confirm the NAS and Mac are on the same network segment (same subnet)
- Try browsing manually: in Finder, Go > Connect to Server, enter
smb://[NAS-IP-address], and connect to the TimeMachine share - Check DSM File Services > SMB is enabled and the Time Machine option is set for the correct share
When you select the share, macOS prompts for credentials. Enter the DSM username and password you assigned Read/Write permission to the TimeMachine folder. macOS will store these credentials in the keychain for future automatic backups.
Click Use Disk. macOS creates a sparsebundle disk image in the TimeMachine folder and begins the first backup. The initial backup can take hours for a large system. Let it run overnight.
Step 4. Monitor and Manage Backups
Time Machine creates one .sparsebundle file per Mac in the TimeMachine shared folder. Open File Station on DSM to see these. The size of the sparsebundle reflects current backup usage. It grows as backup history accumulates and shrinks when old snapshots expire past the retention window.
To verify backups are running: on the Mac, click the Time Machine icon in the menu bar. It shows the last successful backup time and current status. If it shows 'Last backup: more than 24 hours ago', check that the NAS is powered on and the Mac is connected to the same network.
For multiple Macs, each creates its own sparsebundle in the same TimeMachine folder. They don't interfere with each other. Monitor the total folder size in Storage Manager to ensure you're staying within your volume capacity.
Recovering Files with Time Machine from NAS
File recovery works the same way as with a local Time Machine drive. On the Mac, open Time Machine from the menu bar, browse to a previous date, navigate to the folder or file you want to recover, and click Restore. macOS retrieves the file from the NAS sparsebundle over the network.
For recovery to the source Mac, start macOS Recovery and select Restore from Time Machine. For a new or different Mac, use Setup Assistant or Migration Assistant to transfer from the Time Machine backup. You'll need to be on the same network as the NAS, and the NAS needs to be powered on and accessible. The restore streams data from the NAS over SMB. A large network restore can take hours; duration varies with network, Mac and NAS performance and the backup's file mix.
Wired Ethernet strongly recommended for both backup and restore. Wi-Fi works, but a Gigabit wired connection is substantially faster and more reliable for large data transfers. If your Mac only has USB-C/Thunderbolt ports, a USB-C to Gigabit Ethernet adapter ($20-40 from most AU electronics retailers) solves this.
Hardware and AU Pricing
Time Machine works on any Synology NAS, including ARM models that don't support Docker. The simplest option for a Mac-focused home network is the DS225+ (~$638 at Mwave) with two 4TB NAS drives selected in line with Synology's current drive-compatibility guidance; check current retailer pricing. 4TB usable in RAID 1, Check current component pricing before budgeting the total. That comfortably backs up 1-2 Macs with generous retention history.
If Time Machine is the primary use case and budget is a consideration, the DS223 (check current Mwave pricing) is a more affordable entry point. It uses an ARM CPU so it won't support Docker containers, but Time Machine, file sharing, and Synology Photos all run fine on ARM models.
Compare this to Apple's discontinued AirPort Time Capsule (last sold in 2018. And no longer receiving security updates). A current multi-bay Synology NAS configured with a redundant RAID level can provide drive-failure protection and additional NAS functionality. Qualifying purchases from Australian-based retailers are generally covered by Australian Consumer Law consumer guarantees, subject to the law's scope and exceptions.
Related reading: our NAS buyer's guide, our Synology brand guide, and our 3-2-1 backup guide.
Use our free Backup Storage Calculator to size your backup storage correctly.
See also: our complete Synology NAS Australia guide.
See also: our full Backup and Disaster Recovery guide.
Does Time Machine work over Wi-Fi with a Synology NAS?
Yes, Time Machine over Wi-Fi works. But it's slower than wired Ethernet. The backup runs in the background, so speed matters most for the initial backup and for restores. Wi-Fi throughput and initial-backup time vary with the Mac, access point, distance, interference, file mix and NAS load. On 2.4GHz or a weak signal, expect significantly longer. For day-to-day incremental backups (usually under 1GB), Wi-Fi is perfectly adequate. For full system restores, use wired Ethernet if possible.
Can multiple Macs back up to the same Synology NAS?
Yes. Each Mac creates its own sparsebundle file in the TimeMachine shared folder. Multiple Macs can back up concurrently. Though simultaneous large backups will slow down each other and the NAS. A practical setup is staggering backup schedules (or just letting macOS manage it. Time Machine naturally spreads out backup windows). For 3+ Macs, consider a 4-bay NAS like the DS425+ for more storage capacity.
Why does macOS say 'Backup Failed' or 'Disk Not Available'?
Common causes: (1) The NAS is asleep or powered off. Check DSM Power Management settings and disable HDD hibernation if you want instant backup availability. (2) The Mac and NAS are on different network segments (some routers with multiple VLANs isolate devices). (3) The SMB Time Machine option was changed in DSM. Check Control Panel > File Services > SMB > Advanced > Time Machine and confirm the correct share is selected. (4) If the backup bundle is unusable, troubleshoot it first and retrieve any needed files. Deleting the bundle is a last-resort reset that permanently removes the existing backup history and starts a new full backup.
Can I use the same NAS for both Time Machine (Mac backup) and Active Backup (PC backup)?
Yes, on a Synology model that supports Active Backup for Business and uses a Btrfs volume. Time Machine and Active Backup for Business then operate independently. They coexist on the same NAS without conflict. Use separate shared folders for each (e.g. TimeMachine for Mac, separate ABB destination for PCs) to keep storage usage visible and separately quotaed.
Does the NAS need to stay powered on 24/7 for Time Machine to work?
Time Machine only backs up when it can reach the NAS. The NAS must be powered on and reachable. Ordinary drive hibernation normally ends when the NAS is accessed, although waking the drives can add a delay. For reliable hourly backups, set the NAS to wake on LAN activity or disable hibernation entirely (Storage Manager > HDD/SSD > HDD Hibernation > set to 'Never'). Alternatively, set Time Machine to daily backups. It's less likely to hit a hibernation window. For home use, leaving the NAS running is typically fine; a 2-bay NAS draws 10-20W, costing $3-6/month at Australian electricity rates.
Can I use a Synology NAS as a Time Machine target for an Apple Silicon Mac?
Yes. Apple Silicon Macs (M1, M2, M3, M4) use the same macOS Time Machine system and work identically with a Synology NAS SMB share. The restore process on Apple Silicon is slightly different (hold power button to enter recovery mode rather than Cmd+R) but the NAS-based restore works the same way. Keep DSM updated to the latest version available for your Synology model.
How Much Storage to Allocate to Time Machine on NAS
On Btrfs-capable models, DSM supports a shared-folder quota; otherwise use the applicable user or volume quota. Without a quota, Time Machine will use as much space as it can, eventually filling the entire NAS. Set the quota to roughly 2 to 3 times the size of the Mac's internal storage as a starting point. For a MacBook Pro with a 1TB SSD, allocate 2 to 3 TB to Time Machine. For a Mac Studio with a 2TB SSD, allocate 4 to 6 TB.
Time Machine stores incremental hourly backups for 24 hours, daily backups for the past month, and weekly backups for all previous months. Incremental-backup size varies with how much data has changed since the previous backup, but the full initial backup equals the size of your Mac's used storage. Initial-backup time varies substantially with effective network throughput, file mix, Mac performance and NAS load.
Storage formula: Time Machine quota = (Mac internal SSD size) x 2.5. For a 512 GB MacBook: allocate 1.28 TB. For a 2 TB Mac Studio: allocate 5 TB. Actual retention varies with the Mac's used capacity and rate of data change; Time Machine prunes older backups when space is needed.
Running Time Machine for Multiple Macs on One NAS
A Synology NAS can serve as a Time Machine destination for multiple Macs simultaneously. Create a separate shared folder for each Mac (e.g. TimeMachine-MacbookPro, TimeMachine-iMac) with an individual quota per folder. In Time Machine Preferences on each Mac, select the corresponding shared folder when setting up the backup destination. This keeps each Mac's backup history separate and prevents one Mac from consuming another's allocated quota.
Performance note: simultaneous backups from multiple Macs over WiFi can compete for bandwidth and slow each other down significantly. If more than two Macs are backing up simultaneously, connect them via Ethernet or stagger backup schedules using Time Machine's backup interval setting (available via the terminal command: use Time Machine Settings > Options > Back up frequency on macOS Ventura or later).
Limitations: What Time Machine on NAS Cannot Do
Time Machine on a Synology NAS has two important limitations compared to Time Machine on a directly connected drive. First: Time Machine backups over the network (SMB) are stored as a sparse bundle disk image, not as individual files directly browsable on the NAS. You cannot browse Time Machine backup contents through the NAS file manager; access the backup through Time Machine, Setup Assistant or Migration Assistant on an authorized Mac rather than through the NAS file manager.
Second: restoring from a network Time Machine backup when the Mac cannot boot (for example, to restore to a new Mac or reinstall macOS) requires the NAS to be accessible during the recovery process. This means the NAS must be on the same network as the Mac being recovered. If you are recovering from a macOS bootable USB or in Recovery Mode, the NAS must be reachable over the LAN before the recovery begins. An external Time Machine drive plugged directly into the Mac does not have this dependency.
Can Time Machine back up to a NAS over WiFi instead of Ethernet?
Yes, Time Machine over WiFi works, but the initial backup is much slower. Initial-backup time varies substantially with effective Wi-Fi or Ethernet throughput, interference, file mix and NAS load. Once the initial backup completes, hourly incrementals over WiFi are fast (usually 5 to 15 minutes). If possible, connect the Mac via Ethernet for the initial backup and switch to WiFi for incrementals after.
Does Time Machine backup over a NAS protect against ransomware?
Partially. Time Machine backups over SMB use a sparse bundle stored within a writable network share, so the bundle should not be treated as inherently protected from alteration or deletion. A Time Machine bundle on a writable SMB share should not be assumed to resist ransomware; protect it with restricted permissions, immutable snapshots where supported, and an additional offline or off-site copy. However, ransomware that compromises the Mac itself could corrupt the sparse bundle from within the Mac's own filesystem. The stronger protection is enabling Snapshot Replication on the Synology NAS for the Time Machine shared folder, creating read-only point-in-time copies; where supported, enable immutable snapshots to prevent their deletion during the configured protection period.
Also backing up Windows PCs to the same NAS? Synology Active Backup for Business handles Windows PC and server backup at no extra licence cost. Pairs perfectly with Time Machine for a mixed Mac/Windows household.