Are you involved in the Synology Cloud Sync not working problem? If so, try to fix it with the 8 quick solutions in this post. Moreover, you will be shown with a free Synology Cloud Sync alternative โ MultCloud Cloud Sync, to ease your anxiety immediately.
I've been syncing files from my NAS to Box using Synology Cloud Sync. Since it affects how we grant employees remote access to files, this is a crucial issue for us. Our employees can access the files on the NAS from anywhere at any time after they sync to Box. The Box API is currently denying authentication and returning a 403 error. If this isn't resolved right away, I'll have to remove Box from my employees' current access.
If you find Synology cannot be synced due to access permission denied, you can check the 8 factors to see whether they echo your situation.
♦Inaccurate Credentials: Verify that you are using the right credentials for the cloud service. Verify your login credentials again.
♦OAuth Token Expiration: OAuth tokens are used by certain cloud services (such as Dropbox and Google Drive). These may become invalid or expire. In Cloud Sync, try reconnecting or re-authenticating the cloud service.
♦Not Enough Permissions: Verify that Cloud Sync is authorized to access the cloud storage. Certain cloud providers demand that third-party apps be given particular access privileges.
♦Two-Factor Authentication: You may need to create an application-specific password or reauthenticate if your cloud service employs two-factor authentication (2FA).
♦Firewall Blocking: Verify whether your router or firewall is preventing Synology from connecting to the cloud. To permit traffic from Synology NAS to the cloud service, you might need to modify the firewall settings.
♦DNS or Proxy Problems: Make sure that your custom DNS settings or proxy server aren't preventing Cloud Sync from connecting to the cloud.
Compatibility with third-party services may be affected by updates or changes made to some cloud providers' APIs. Make sure your version of Cloud Sync is current and that the cloud provider's API hasn't changed.
Verify that you have the most recent version of Synology Cloud Sync installed. Updates occasionally fix bugs that could prevent access or deal with compatibility issues with cloud services.
♦Exceeded Cloud Quota: Cloud Sync access may be refused if the cloud account's storage quota has been exceeded. Make sure your cloud account has enough storage available.
♦Limits on Cloud Sync Quota: Certain services have a limit on the number of connections or operations they can manage at once. Verify whether you've reached these limits.
Verify the Cloud Sync configuration again. Make sure there are no configuration errors that could prevent access and that the synchronization settings (such as folder mappings or filters) are configured correctly.
There may be some problems with the DSM version. Updates to DSM (DiskStation Manager) can occasionally bring bugs that impact Cloud Sync. Try looking through Synology's forums or support site to see if anyone else is having the same problem if it happened after a DSM update.
If the above solutions cannot help you resolve the Synology Cloud Sync not working issue, there is another workaround for you – MultCloud Cloud Sync. MultCloud is a professional cloud management service that supports more than 30 cloud drives, including Google, Dropbox, Box, Google Shared Drive, MEGA, Backblaze B2, Amazon S3, iCloud Drive, Google Photos, etc.
Like Synology Cloud Sync, you just need to connect your Synology NAS and the cloud drive to MultCloud, and you can create a sync task to sync files between them. The process is automatic and does not need you to download or upload any file.
Besides, MultCloud Cloud Sync also gives the Schedule feature that you can set the sync process to auto-start at any time you like. Moreover, MultCloud Cloud Sync can give you 10 sync modes, such as:
Since MultCloud supports so many cloud drives, here only use syncing files from Synology NAS to Box as an example to show how to use MultCloud Cloud Sync.
Step 1. Go to the MultCloud website and sign up for a free account.
Step 2. Add NAS to MultCloud by clicking Add Cloud and the NAS logo. Then, add Box using the same step.
Step 3. Select Cloud Sync in the left sidebar and choose NAS as the source and Box as the target.
Step 4. Open Options to choose a sync mode if you need it. Finally, tap on the Sync Now button to start syncing.
Note: MultCloud uses data traffic to sync files and you can get 5 GB of free traffic per month. However, if you have a large number of files to sync in a month, you can subscribe to a paid to get 100 GB to lifetime unlimited data traffic.
If you are facing the Synology Cloud Sync being denied access issue, you can check the above 8 fixes one by one to see if they can help you. If none of them make sense and Synology Cloud Sync access is denied still, you can use MultCloud Cloud Sync instead of Synology Cloud Sync to sync files between Synology NAS and a cloud drive. MultCloud gives 30+ cloud options and the sync task is also automatic.