Synology Shared Folder Sync copies a shared folder one way from a source NAS to a destination NAS over rsync. In DSM 7, you’ll find it on the source NAS at Control Panel > File Services > Advanced > Shared Folder Sync, so if you looked at every Control Panel icon and came up empty, that’s why.
I set this up between two NAS I’d named DSM-Source and DSM-Destination when I first wrote this in May 2021, when it still had its own icon. The path and labels below are Synology’s DSM 7.4 ones, checked in September 2026.
Shared folder synchronization is a one-way copy from a source Synology NAS to a destination. You pick shared folders on the source, point a task at the destination, and DSM keeps them matching on the schedule you set, so the first run copies everything and every run after it sends only what changed.
It runs over rsync (DSM supports rsync 3.1.2), and unlike Snapshot Replication there’s no Btrfs requirement, so it’s the option for ext4 volumes. Synology’s help page has the full list of what it won’t sync.
In DSM 7 it lives at Control Panel > File Services > Advanced: scroll down to Shared Folder Sync, the second-to-last block, right above Bypass Traverse Checking, and the tasks are in its Task List. It isn’t in the Control Panel grid because it stopped being its own section, and the DSM release notes for 7.0-41890 (June 29, 2021) put it in one line: “Moved Shared Folder Sync into the File Services tab”.
- Destination NAS: the same path, then Connection List, which holds its pairings and the Unlink button
- DSM 6.2 and earlier: Control Panel > Shared Folder Sync > Task List
If the Control Panel won’t open, or opens without File Services, that’s the account: only the administrators group gets all of it. Ask an admin to add yours at Control Panel > User & Group. Application Privileges is separate. Control Panel > Application Privileges > rsync > Edit decides who may use rsync there. Tick Allow for that user, click OK, and check the Group tab too, because a Deny there beats an Allow. A denial shows up as the wizard refusing your login, not a missing menu.
Setup starts on the destination NAS, the side accepting the connection. It’s the same service you’d enable to back up a Linux PC with rsync.
1. Give the two NAS different server names at Control Panel > Network > General, or the task fails with error 213.
2. On the destination NAS, open Control Panel > File Services > rsync, tick Enable rsync service, and select Apply. Also tick Enable SSH service at Control Panel > Terminal & SNMP > Terminal and select Apply, or the task fails with error 49. Don’t pre-create the sync folder here: DSM makes one with the source’s name and renames any existing folder of that name by adding _1.
3. On the source NAS, open Control Panel > File Services > Advanced and select Task List under Shared Folder Sync.
4. Select Create, name the task (1 to 32 characters, and DSM rejects most punctuation), then select Next.
5. Select the shared folders to sync, tick the checkbox to accept the disclaimer, then select Next.
6. Enter the destination’s IP address or server name and sign in with an account in its administrators group that is allowed under Application Privileges. Over the Internet, use the external IP or an FQDN.
7. Set the transfer options: Customize SSH encryption port for encrypted shared folder sync if you moved it off 22, Enable SSH transfer encryption, Enable transfer compression, Enable block-level synchronization, and Sync remote mounted folders for CIFS and NFS mounts. Click Test connection on that same screen before Next.
8. Choose when it runs, then select Next: Run sync on modification, Run sync manually, or an Advanced schedule using Schedule Plan. A scheduled task won’t run if nothing changed.
9. Review the summary and select Done. The task runs on the schedule from step 8, or select it and click Sync Now for the first sync.
10. Check the destination: the new folder shows up in File Station and under Control Panel > Shared Folder, where you grant users access at Edit > Permissions. The first run also drops the task’s account to Read Only under Edit > Advanced Permissions, which is normal for a live sync destination.
How to Sync Folders Between Two Synology NAS
To make one Synology sync folders to another, both ends have to be a Synology NAS and the work is on the receiving side: enable rsync there and the source does the rest.
Over the LAN there’s nothing more to do once rsync is on at the destination. Over the Internet, forward the ports to the destination, the side running the rsync service: 873 for rsync, plus 22 when SSH transfer encryption is on. QuickConnect does not work for this, it needs an IP or a DDNS address. Tick Enable SSH transfer encryption for anything crossing the Internet, and keep an eye on that port. Security changes, so nothing here is guaranteed.
Can You Sync Two Folders on the Same Synology NAS?
No. Shared Folder Sync runs between two devices and needs two different server names, which one NAS cannot satisfy, so you land on error code 213.
Snapshot Replication does it locally if both volumes are Btrfs, and Hyper Backup copies a folder to another folder on the same NAS if you pick Single version at the destination, since the default writes .hbk files only Hyper Backup can open.
Four NAS-to-NAS tools come up for Synology folder sync, and picking the wrong one is most of the pain. For most people it’s simple: ext4 and a second NAS, use this; Btrfs on both ends, Snapshot Replication; anything you’d call a backup, Hyper Backup.
| Tool | What it does |
|---|---|
| Shared Folder Sync | One-way mirror over rsync, no versions, no Btrfs needed |
| Snapshot Replication | Point-in-time snapshots, local or remote, Btrfs on both ends, read only at the destination |
| Hyper Backup | Versioned, restorable backup to a local folder, remote NAS, rsync server or cloud |
The fourth tool is Synology Drive ShareSync, the two-way option inside Synology Drive Server, and for a PC or Mac it’s Synology Drive Server and Drive Client. I’ve covered Snapshot Replication and Hyper Backup separately.
Synology still ships it, and it’s in the DSM release notes. The 7.3 entry, October 2025: “Fixed an issue where DSM configuration backups or Hyper Backup could fail while Shared Folder Sync tasks were running”.
Files removed from the source are removed from the destination, so if the data there is deleted, corrupted or encrypted by ransomware, the next run copies that state straight to your second NAS.
Snapshots are the first line of defense I’d want in front of this, and on ext4 you do not get them, so the backup behind this is your whole recovery plan: Hyper Backup, or a backup to a remote Synology NAS.
If it fails the moment it runs, check the two setup requirements first: different server names, and rsync on at the destination. When a task fails mid-run, DSM gives you an error code in the Log Center app. The task is on the source NAS at Control Panel > File Services > Advanced > Shared Folder Sync > Task List, where every fix below starts. The codes come from Synology’s error code table.
| Code | What it means | What to check |
|---|---|---|
| 43, 210 | rsync isn’t enabled on the destination | Destination NAS, Control Panel > File Services > rsync, tick Enable rsync service, then Apply |
| 44 | Wrong password | Source NAS, Edit > Destination, re-enter the password |
| 211 | The account isn’t an administrator | Source NAS, Edit > Destination, use an admin account |
| 213 | Both NAS have the same server name, or a folder name is over 32 characters | Either NAS, Control Panel > Network > General > Server name, change one; or shorten the folder name on the source |
| 53 | No permission on the destination folder | Source NAS, Edit > Destination for the username; destination NAS, Control Panel > Shared Folder > Edit, set that user to Read only or higher on the Permissions tab and under Advanced Permissions > Advanced Share Permissions |
| 49 | SSH is off on the destination, or the port is wrong | Destination NAS, Control Panel > Terminal & SNMP > Terminal, tick Enable SSH service, then Apply; if SSH is on, source NAS, Edit > Destination, tick Customize SSH encryption port for encrypted shared folder sync and enter the port from that Terminal page |
| 50 | The source IP has been blocked | Destination NAS, Control Panel > Security > Protection > Auto Block > Allow List/Block List, remove the source’s IP |
| 30 | The task stalls or times out | A sparse file (source NAS, Edit > Destination, untick Enable block-level synchronization), a huge file, or too many files in one folder |
| 255 | An encrypted shared folder’s encryption mode | Source NAS, Edit > Destination: check credentials. Destination NAS, Control Panel > Shared Folder > Edit > Permissions: that account needs read permission on the encrypted folder. Untick Enable SSH transfer encryption on the source, rerun for the real code, and re-tick it once the task runs |
| 23, 24, 208 | A file vanished mid-sync, the two sides disagree, or the destination folder was renamed | Check the destination folder’s name, then run Full Sync (it re-copies everything) |
Synology has a whole article on error 53: if the task never worked, it’s the account’s permissions on the destination folder. If it worked and then stopped, it’s a UID mismatch: the two NAS keep separate user lists and the sync has overwritten a destination user’s permissions. Synology’s fix is to match the UIDs: join both NAS to the same domain or LDAP server, or restore the source’s user and group settings on the destination. Three things read like a failure and aren’t. #recycle is skipped unless it sits inside an encrypted source folder, and external storage is not supported at all. The Docker shared folder can’t be watched, so it syncs on a schedule or a manual run, never on modification.
The failure that costs people data isn’t the loud one. It’s the task you think is syncing and isn’t, so set up alerts at Control Panel > Notification rather than trusting a green Task List.
How to Pause, Stop, or Delete a Sync Task
There’s no Pause button. The source’s Task List gives you Create, Edit, Delete, Cancel, Sync Now and Full Sync. Cancel stops a run in progress, but on a task set to Run sync on modification any change starts it again, so the working pause is to Edit the task and switch it to Run sync manually.
Delete removes the task from the source and leaves the copy on the destination. Set the access you want at the destination’s Control Panel > Shared Folder > Edit > Permissions, and clear the read-only rule at Edit > Advanced Permissions. It’s the clean ending for a migration, but don’t use it as a pause: recreating the task re-transfers the whole folder. To break the pairing, sign in to the destination, open Control Panel > File Services > Advanced > Shared Folder Sync > Connection List, select the source and click Unlink; the data stays.
Overall, this took one Control Panel wizard to get running when I set it up, and it still does the job without a package to install or a client to keep updated. Give it a schedule that matches how often the source changes, and keep a real backup behind it.
