Why Your Mac Deserves Better Than a USB Drive
Time Machine is one of macOS’s most reliable built-in features – a background backup system that quietly snapshots your entire drive on a schedule, so when something goes wrong, you can roll back minutes, hours, or weeks. The problem is that most people either never set it up at all, or they plug in a single external drive that sits on their desk until it fails. A Synology NAS changes that equation by turning network storage into a proper, always-on backup destination that works automatically whenever your Mac is on the same Wi-Fi network.
Setting up a Synology as a Time Machine server is not especially complicated, but it does require navigating a few different control panels and making decisions about storage limits before anything works. This guide walks through the entire process – from preparing the NAS to confirming the first backup completes – so you end up with a setup that actually runs without manual intervention.
Preparing Your Synology NAS
Before touching Time Machine settings on your Mac, the NAS needs to be configured to accept backup connections. Open DSM (DiskStation Manager) in a browser, log in as an administrator, and head to Control Panel > File Services > AFP. Enable AFP (Apple Filing Protocol) – this is the legacy protocol Time Machine uses to communicate with network volumes. On newer versions of DSM, Synology also supports SMB-based Time Machine backups, but AFP remains the most straightforward path for compatibility across macOS versions.
Next, create a dedicated shared folder for Time Machine data. Go to Control Panel > Shared Folder and click Create. Name it something obvious like “TimeMachine” and choose which volume it lives on. During setup, enable data checksums if your file system supports it – this catches silent data corruption, which matters more for backup data than almost anything else. Avoid enabling the recycle bin for this folder, since Time Machine manages its own internal versioning and the recycle bin just consumes space without adding protection.
With the shared folder created, set a storage quota to prevent Time Machine from consuming the entire drive. Select the folder, click Edit, and navigate to the Advanced tab to assign a size limit. A good rule of thumb: allocate roughly two to three times the size of your Mac’s internal storage. A 512GB MacBook Pro, for example, works well with a 1TB to 1.5TB quota. Time Machine will rotate out old backups automatically once it hits that ceiling, keeping the most recent snapshots.
Creating a Backup User Account
Time Machine connections to a NAS require valid credentials, and using your main admin account for this is sloppy security practice. Instead, create a separate user specifically for backups. In DSM, go to Control Panel > User and Group, add a new user – call it something like “timemachine-user” – and give it a strong password. Under folder permissions for this account, grant read/write access to the TimeMachine shared folder only. No other permissions are needed.
Once the user exists, go back to the TimeMachine shared folder settings, click Edit, and under the Time Machine tab, enable “Enable this shared folder as a Time Machine backup destination.” DSM will ask which users are allowed to back up here – select the dedicated backup user you just created. This step is easy to skip, but without it, macOS may not recognize the folder as a valid Time Machine target.
Connecting Time Machine on Your Mac
On your Mac, open System Settings (or System Preferences on older macOS versions) and navigate to General > Time Machine. Click “Add Backup Disk.” Your Synology should appear in the list if both devices are on the same network and AFP is enabled. If it does not appear, open Finder, press Command+K to open the Connect to Server dialog, and type afp://[your NAS IP address] – this forces macOS to mount the NAS volume manually before Time Machine can detect it.
When prompted for credentials, enter the dedicated backup user account details you created on the NAS. macOS will ask whether to encrypt the backup – this is worth enabling if the NAS stores data in a shared household or office environment, since an encrypted Time Machine sparsebundle cannot be read without the password even if someone gains physical access to the drive. Encryption does add some overhead to backup operations, but for most users the performance difference is minor enough to ignore.
After selecting the disk and confirming credentials, Time Machine will schedule an initial backup within the next two minutes. The first backup is always the longest – it copies your entire system, not just changes – so running it overnight or while the Mac sits idle on its charger makes sense. Subsequent backups run every hour by default and only transfer changed or new files, keeping them fast. You can adjust backup frequency using the Time Machine settings panel or through a free utility like TimeMachineStatus, which surfaces more detail about what the backup system is actually doing.
One detail worth getting right before that first backup runs: verify your Mac stays awake long enough to complete it. Go to System Settings > Battery > Options and enable “Enable Power Nap” or “Prevent automatic sleeping when display is off” while the first backup runs. A Mac that goes to sleep mid-backup will pause and resume, but if it happens repeatedly the initial backup can drag on for days. After the first full backup completes, incremental backups are quick enough that sleep behavior rarely matters.
Verifying Backups and Keeping Things Running
Once the initial backup finishes, open Time Machine settings and confirm the “Latest Backup” timestamp reflects the completed session. Spot-check by clicking “Browse Time Machine Backups” – this opens the familiar Time Machine interface where you can navigate back through snapshots and confirm files are actually there and recoverable. A backup setup that has never been tested for recovery is not really a backup setup.
Ongoing maintenance is minimal. DSM will log Time Machine activity under Log Center, and any failed backup attempts – usually caused by network interruptions or credential issues after a password change – will show up there. If you ever change the backup user’s password on the NAS, update it in macOS Keychain as well, or Time Machine will silently fail until you re-authenticate. That silent failure is the most common reason people discover their backup hasn’t run in three weeks.
If you run multiple Macs in the same household, each device can back up to the same TimeMachine shared folder on the NAS, provided each Mac authenticates with the same backup user account and the folder quota is sized accordingly. DSM creates a separate sparsebundle file inside the shared folder for each machine, named by the Mac’s hostname and hardware UUID, so the backups stay independent even though they share the same destination folder.
For users who also want off-site or remote access to their NAS – for instance, to verify backups while traveling – configuring secure remote access through a solution like Tailscale VPN keeps the NAS reachable without exposing its management interface to the public internet. Time Machine itself does not back up over VPN efficiently, but the ability to check backup status and access files remotely adds a practical layer of peace of mind that a local-only setup cannot provide.
