Synology NAS Error Code 53: How to Fix SMB Authentication Failed

Easy 10-20 minutes Medium Severity Verified June 2026
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Error Code
53
Brand
Synology
Product Type
nas
Severity
Medium
DIY Difficulty
Easy
Estimated Fix Time
10-20 minutes
Error code 53 on a Synology NAS indicates that SMB (Server Message Block) authentication failed. This usually happens when your computer cannot connect to the shared folder due to incorrect credentials, protocol mismatch, or security settings. The fix involves adjusting DSM settings and checking your device's network configuration.
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Tools You'll Need

How to Fix Error Code 53

  1. Check SMB Service Status on DSM

  2. Verify SMB Protocol Version

    SMB1 is less secure; use only if necessary for legacy devices. Consider upgrading your clients instead.

  3. Confirm User Credentials

  4. Check Windows Credential Manager (Windows)

  5. Check macOS Keychain (Mac)

  6. Restart SMB Service

  7. Update DSM and Network Drivers

    Back up your DSM settings before major updates.
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When to Call a Professional

If you've tried all steps and still get error 53, contact Synology support or a network specialist. Persistent issues may indicate a deeper network conflict or hardware problem.

Frequently Asked Questions

What does error code 53 mean on Synology?
It means SMB authentication failed – your computer couldn't connect to the shared folder due to incorrect credentials, outdated SMB protocol, or a security mismatch.
How do I fix SMB authentication failed on Synology?
Follow our steps: enable SMB in DSM, set the minimum SMB protocol, verify user permissions, clear saved credentials on your computer, and restart the SMB service.
Do I need to enable SMB1 for Windows 10 to connect?
Windows 10 typically works with SMB2/3. Only enable SMB1 if you have older devices like Windows 7 or certain media players. SMB1 is less secure.
Can a firewall cause error 53 on Synology?
Yes, a firewall on your computer or router can block SMB ports (445, 139). Temporarily disable the firewall to test, then create an exception for Synology.
What if I forgot my Synology admin password?
Use the reset button on your NAS (hold 4 seconds until beep) to reset admin password to default. Then log in with default credentials (admin / blank) and set a new password.

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