How to Use macOS Time Machine with a Network Attached Storage (NAS) Drive

The Limitations of USB Time Machine Backups

Time Machine is Apple’s incredibly reliable, built-in backup solution for macOS. Historically, most users set up Time Machine by plugging an external USB hard drive directly into their MacBook or iMac. While this works perfectly for desktop computers that rarely move, it is a deeply flawed workflow for MacBook users.

If you have to remember to physically plug in a USB drive every time you want to back up your laptop, you will eventually forget. Months will pass without a backup, and when a catastrophic SSD failure or theft occurs, your data will be gone. The solution is to decouple the backup drive from the Mac by using a Network Attached Storage (NAS) drive. A NAS connects directly to your Wi-Fi router, allowing Time Machine to back up your Mac wirelessly and automatically, whenever you are connected to your home network.

Requirements for Network Time Machine Backups

To successfully configure this setup, you need the following:

• A Mac running macOS Catalina (10.15) or later.
• A NAS device connected to your local network via an Ethernet cable (brands like Synology, QNAP, or Western Digital My Cloud are popular choices).
• The NAS must support Time Machine over SMB (Server Message Block), which is the standard file-sharing protocol for modern macOS and Windows systems. Older NAS devices using the deprecated AFP (Apple Filing Protocol) may experience severe reliability issues on newer macOS versions.

Step 1: Configure the NAS for Time Machine

Before macOS can use the NAS, you must prepare a dedicated space for it on the storage device.

1. Log into your NAS device’s web administration interface (usually accessed by typing the NAS IP address into your browser).
2. Navigate to the Shared Folders or Storage Management section.
3. Create a new Shared Folder specifically for backups. Name it something obvious, like MacBackup.
4. Crucial Step: Assign a strict storage quota to this folder. Time Machine is designed to consume all available space until the drive is full before it begins deleting old backups. If you do not set a quota (e.g., 1TB on a 4TB NAS), Time Machine will eventually consume your entire NAS, leaving no room for your other files.
5. Ensure the SMB service is enabled in your NAS control panel and that “Bonjour Time Machine broadcast via SMB” is activated (the exact wording varies by manufacturer).
6. Create a dedicated NAS user account (e.g., TM_User) with a strong password, and grant this user read/write access to the MacBackup folder.

Step 2: Connect macOS to the NAS Shared Folder

Now that the NAS is broadcasting the Time Machine folder over your network, you must mount it on your Mac.

1. Open Finder on your Mac.
2. From the top menu bar, click Go > Connect to Server… (or press Cmd + K).
3. Type smb://[NAS_IP_Address] (e.g., smb://192.168.1.50) and click Connect.
4. When prompted for authentication, enter the username (e.g., TM_User) and password you created in Step 1.
5. Check the box to Remember this password in my keychain.
6. Select the MacBackup volume from the list of available shares to mount it to your desktop.

Step 3: Configure Time Machine

With the NAS drive successfully mounted over SMB, you can now instruct Time Machine to use it.

1. Click the Apple menu () and open System Settings (or System Preferences).
2. Navigate to General > Time Machine.
3. Click Add Backup Disk (or the + icon).
4. A list of available drives will appear. You should see your MacBackup NAS folder listed with a green Time Machine icon. Select it and click Set Up Disk.
5. macOS will ask if you want to encrypt the backup. Always choose to encrypt network backups. Enter a strong password that you will not forget (if you lose this password, the backup is completely unrecoverable).
6. Click Done.

Monitoring the First Network Backup

Time Machine will begin a countdown and initiate the first backup. Because this initial backup transfers the entire contents of your Mac over Wi-Fi, it can take anywhere from a few hours to an entire day, depending on your router speed and the amount of data.

It is highly recommended to leave your MacBook plugged into power and, if possible, connected directly to the router via Ethernet for this very first backup to ensure stability and speed. All subsequent backups will be incremental, transferring only the files that have changed, which happens silently and rapidly over Wi-Fi in the background.