Remove the drive as your backup disk in Time Machine, then open your terminal and run. beware that running this command will remove any other existing time machine destination disks!

sudo tmutil setdestination smb://uruser:urpass@NAS_IPADDRESS/TimeMachineName

If you don't want to remove all the existing destinations, you can pass the -a argument.

sudo tmutil setdestination -a smb://uruser:urpass@NAS_IPADDRESS/TimeMachineName

Source

Answer from curmil on Stack Exchange
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Synology Community
community.synology.com › enu › forum › 17 › post › 111010
Lost user password for Time Machine Backup
November 9, 2017 - Hi! Come and join us at Synology Community. A place to answer all your Synology questions. Ask a question or start a discussion now.
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Synology Community
community.synology.com › enu › forum › 1 › post › 126530
Wrong password when trying to restore a time machine backup | Synology Community
June 20, 2019 - I'm not sure if it's a bug in macOS Big Sur, an issue because I have a particularly long password (>20 chars) or what the deal is, but it seems that putting the _network_ password in (i.e. the one I use to connect to the NAS share) allows me to mount the Time Machine sparsebundle in Finder – meaning I can at least access the backups and manually take the files I need out of it.
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Reddit
reddit.com › r/synology › time machine says my password is incorrect... its not
r/synology on Reddit: Time machine says my password is incorrect... its not
October 15, 2018 - If you search for "Time Machine" in Keychain Manager it will show you passwords associated with the TM service. ... Hey, DickVomit, just a quick heads-up: seperate is actually spelled separate.
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Apple Community
discussions.apple.com › thread › 250446487
Time Machine change password for account (Synology)
Time Machine has been running for years, never had to access it and cannot find the password. Hint for it could work but cannot find that no matter how I search. Thanks. 649 2 ... Non-Apple NAS devices are unsuitable for use with Time Machine. Peruse this site for hundreds, if not thousands, of problems with Synology devices in particular.
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Synology Community
community.synology.com › enu › forum › 9 › post › 126530
Wrong password when trying to restore a time machine ...
Hi! Come and join us at Synology Community. A place to answer all your Synology questions. Ask a question or start a discussion now.
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Reddit
reddit.com › r/synology › set up new ds220+ but time machine keeps prompting for pw
r/synology on Reddit: Set up new DS220+ but Time Machine keeps prompting for PW
August 13, 2023 - I am new to NAS, I recently replaced my WD My Cloud as it is now obsolete, and trying to learn all about Synology. ... I feel your pain, I'm here for the same reason. Bloody Western digital. ... At least opening finder and pressing CMD + K opens your dialog where you can enter something like smb://<your.and.server> (same url/IP you enter in your browser) that’s the easy part, bit more tricky is setting up a username+password for Time Machine.
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Apple Community
discussions.apple.com › thread › 255211641
How to fix password issue in Apple Time Machine setup ...
October 17, 2023 - This post gives me confidence that there was a hint: About the Time Machine backup password on Mac – Apple Support (UK) So my question is: How do I find the hint for my password for my encrypted backup on my Time Capsule? 1923 2 ... Contact Synology for support.
Find elsewhere
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Synology Community
community.synology.com › enu › forum › 1 › post › 162087
Unable to access Time Machine backup from Mac recovery
August 5, 2023 - Hi! Come and join us at Synology Community. A place to answer all your Synology questions. Ask a question or start a discussion now.
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Apple Community
discussions.apple.com › thread › 7416753
time machine cannot connect to synology d… - Apple Community
January 11, 2016 - So thus far I reset the password again and tried to reselect the disk and I get the error shown below with keychain - Seems the usual undecipherablekeychain message please help ! ... I fixed this myself. I removed the synology backup drive from time machine. Then switched off TM and closed exited time machine and restarted.
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Reddit
reddit.com › r/synology › best way to encrypt time machine backups and other folders?
r/synology on Reddit: Best way to encrypt Time Machine backups and other folders?
February 10, 2021 -

What is the recommended way to encrypt the Time Machine backup and other folders on the Synology NAS? I want to ensure that if someone physically steals the NAS, they can't just easily view all of its contents.

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Admin Intelligence
blog.admin-intelligence.de › home › time machine backup on the synology nas
Time Machine Backup on the Synology NAS - blog.admin-intelligence.de
April 22, 2025 - Click on “Add Backup Volume..” and select your Synology NAS and choose configure volume… · Enter the login credentials of the previously created Time Machine user and press connect. Here you can optionally select encryption, but make sure to keep your password safe or preferably store it in a Password Manager, so you can still access your data in case of an error.
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NAS Compares
nascompares.com › answer › how-to-set-up-time-machine-backup-on-synology-nas
How to set up Time machine backup on Synology NAS - NAS Compares
January 23, 2023 - Choose the shared folder that you created (i.e., Time Machine Folder on “Server name of your Synology NAS.local”) and click Use Disk. The system will prompt you to provide your account credentials. Enter the username and password for the user that you have just created and click Connect.
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Synology Community
community.synology.com › enu › forum › 5 › post › 185915
Unable to connect to time machine from the mac recovery ...
Hi! Come and join us at Synology Community. A place to answer all your Synology questions. Ask a question or start a discussion now.
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Synology Community
community.synology.com › enu › forum › 1 › post › 162684
Synology Community
September 8, 2023 - Hi! Come and join us at Synology Community. A place to answer all your Synology questions. Ask a question or start a discussion now.
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Reddit
reddit.com › r/synology › time machine with its own account or not
r/synology on Reddit: Time Machine with its own account or not
March 17, 2024 -

I struggled to get Time Machine set up when I got the Syno, so I ignored it for a while. Syno 920+ on 7.1, Mac on Sierra.

Trying again following the Synology instructions, it says to go to the server smb://<server> and enter the TM username/password. At this point, the Mac add just uses the username/ password it already has stored for the server, which is the logged-in user. When trying to connect on TM, it asks for a username/password, and in Log centre, I see that it connects successfully. But then when it tries to do the backup, it fails on the Mac with an access error (nothing in Log Cenre). Q1. Shouldn't an access denied error generate a log entry?

So I've changed the user's permissions on the Syno to have RW to the TM share, and it now looks like it's starting to backup.

Q2: is it a problem that the normal user account is doing the TM? (I understand the concept of an account for a service with only aves and permissions to that service)

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Wondershare Recoverit
recoverit.wondershare.com › backup-files › synology-time-machine.html
5 Easy Steps to Backup Files to Synology NAS With Time Machine
Time Machine supports both the SMB and AFP protocol, and it's equipped with everything you need to set up backups for your Synology NAS. Before you can do anything in Time Machine, you will have to create a user by following the steps below: Go to the Control Panel and click on User. Once you're here, you can click on User Creation Wizard. Fill out all the required information and add the name TimeMachine with your desired password.
Published   January 1, 2024
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WunderTech
wundertech.net › home › synology nas › how to backup to a synology nas with time machine
How to Backup to a Synology NAS with Time Machine - WunderTech
May 5, 2025 - NOTE: If you’d like the Time ... Show Time Machine in Menu Bar. 6. Select your Synology NAS’s folder as the destination (in my case, backups), then select Use Disk. NOTE: If you’d like to encrypt the backup, you can select Encrypt backups. A password will be required ...