Create a Time Machine shared folder
Note: This tutorial assumes that you’ve already established a Volume on your Synology NAS.
Step 1: Open File Station → Create → Create New Shared Folder to establish a new shared folder to house your Time Machine backup.
Step 2: On the basic information page of Share Folder Creation Wizard, insert a name into the Name field. I usually choose a name like “Time Machine.” You’ll also need to use the Location field to select a volume. Click Next.
Step 3: Click the Next button on the Encryption page.
Step 4: Click Apply on the Confirm settings page.
Create a Time Machine user
Step 1: Open Control Panel → User → Create to open the User Creation Wizard.
Step 2: Fill out the Name field with “Time Machine” (without quotes) and enter and confirm a desired password. Click Next.
Step 3: Click next on the join groups page.
Step 4: On the assign shared folders permissions page, click the checkbox next to the Time Machine shared folder for Read/Write. Click Next.
Step 5: On the user quota setting page you can designate the amount of space on the volume you’d like to reserve for Time Machine backups. A good rule of thumb is to set the quota at four times the amount of storage space on your Mac. Since I have only 256GB of flash storage on my iMac, I’ll give my Time Machine backup 1TB of storage. Click Next.
Step 6: Click Next on the assign application permissions folder page.
Step 7: Click Next on the user speed limit setting page.
Step 8: Click Apply on the Confirm settings page.
Assign Time Machine backup protocol and location
Step 1: Open Control Panel → File Services and ensure that Enable SMB service is enabled.
Step 2: Click the Advanced tab and check the box next to Enable Bonjour Time Machine broadcast via SMB. Click Apple, and click Yes on the Bonjour Time Machine broadcast via SMB notification.
Step 3: Click the Set Time Machine Folders button → and click the box next to the Time Machine shared folder. Click Apply. Close the DSM Control Panel.