
# Synology Share Says "Network Password Is Not Correct" (System Error 86)? Check Auto Block

**Short answer:** if Windows keeps saying "The specified network password is not correct" when you map a drive to a Synology NAS, and you're sure the password is right, check whether DSM's **Auto Block** has blocked your PC's IP address. In DSM go to **Control Panel > Security > Protection > Allow/Block List**, open the **Block List**, and remove your IP. A blocked IP gets the same "wrong password" error as a real wrong password, so it looks like a Windows problem when it isn't.

That was the cause for a client of mine. Below is what it looked like, what didn't fix it, and how to unblock without switching protection off for everyone.

## The symptom

My client's office uses a Synology NAS as the file server, with a shared folder that staff map as a network drive using a NAS username and password. They had run that setup for years without trouble. Then, fairly suddenly, every Windows 10 and 11 PC refused to connect. Because it started recently, a Windows update was my first suspect.

Windows asked for credentials as usual:

![Windows Security "Enter network credentials" dialog for the NAS](https://storage.googleapis.com/www-tyolab-com-blog-assets/images/blog/incorrect-passwords/2024-05-13-13-00-29.png)

Entering the correct username and password gave this:

![Windows Security dialog showing "The specified network password is not correct."](https://storage.googleapis.com/www-tyolab-com-blog-assets/images/blog/incorrect-passwords/2024-05-13-13-00-56.png)

Mapping the drive from the command prompt failed the same way, with error 86:

```text
C:\>net use h: \\demoserver\data /user:demouser <password>
System error 86 has occurred.

The specified network password is not correct.
```

![net use returning System error 86](https://storage.googleapis.com/www-tyolab-com-blog-assets/images/blog/incorrect-passwords/2024-05-13-12-43-12.png)

(`demoserver` and `demouser` stand in for the real names.)

## What didn't work: changing the LAN Manager authentication level

A lot of advice online for this error says to change the NTLM settings in Local Security Policy:

1. Run `secpol.msc`.
2. Go to **Local Policies > Security Options > Network security: LAN Manager authentication level**.
3. Set it to **Send NTLMv2 response only. Refuse LM & NTLM**.

That setting is worth having anyway: it's the secure option, and current Synology DSM supports NTLMv2. But it didn't fix this problem. Neither did other values such as **Send LM & NTLM - use NTLMv2 session security if negotiated**. Don't leave a weaker setting in place if it doesn't help. Allowing LM or NTLMv1 makes password hashes easier to crack. None of the other fixes I found online worked either, because the problem wasn't on the Windows side.

## The cause: Synology Auto Block

DSM has a protection feature called **Auto Block**. It blocks an IP address once it reaches a set number of failed sign-ins within a time window. This applies to file services like SMB as well as the DSM login. Someone had tried to map the drive with the wrong password too many times, and the NAS blocked the IP.

Once an IP is blocked, the NAS rejects every sign-in from it, including ones with the right password, and Windows reports it as a wrong password. That's why correct credentials kept failing.

Here's the setting, in **Control Panel > Security > Protection**:

![Synology DSM Control Panel, Security, Protection tab, Auto Block section with "Enable auto block" unticked](https://storage.googleapis.com/www-tyolab-com-blog-assets/images/blog/incorrect-passwords/2024-05-13-13-48-24.png)

This screenshot was taken after the fix, so **Enable auto block** is unticked. Note the values shown: 10 failed attempts within 5 minutes triggers a block, and **Enable block expiration** is off. With expiration off, a blocked IP stays blocked until someone removes it by hand. It won't clear itself overnight.

For this client I turned Auto Block off, and the PCs could map the drive straight away. That was acceptable here because the NAS has other security measures in place. Most people should use one of the fixes below instead.

## How to fix it without turning off Auto Block

An earlier version of this post only said to disable Auto Block. That works, but it removes brute-force protection for every service on the NAS. That matters most if DSM, QuickConnect or any file service can be reached from the internet. These fixes are better:

1. **Remove the blocked IP.** Go to **Control Panel > Security > Protection**, click **Allow/Block List**, open the **Block List** tab, select the PC's IP address and delete it. The PC can connect again straight away.
2. **Add your LAN to the Allow List.** On the **Allow List** tab, add your office subnet (for example `192.168.1.0/24`) or the specific PCs. Addresses on the Allow List are never auto-blocked, so typos inside the office won't lock anyone out. Attempts from outside are still blocked.
3. **Turn on block expiration.** Tick **Enable block expiration** and set **Unblock after (days)** so a block clears itself instead of lasting until someone notices.
4. **Find out where the failed logins came from.** One PC with an old saved password (in Windows Credential Manager, a mapped drive set to reconnect at sign-in, or a scanner or backup job) can retry in the background and hit the limit again. DSM's **Log Center** and notifications show which IP was blocked.

To confirm a block before changing anything, look in the Block List for the PC's IP. You can also try the same credentials from a device with a different IP, such as a phone using a file manager app, or a laptop on the same Wi-Fi. If that works and the PC doesn't, the IP is blocked.

## Other causes of System error 86

If your IP isn't in the Block List, these are the usual suspects:

<Table data={{
  "headers": ["Cause", "How to check or fix"],
  "rows": [
    ["Stale saved credentials for the same server", "Run net use to list connections, remove old ones with net use \\\\server\\share /delete, and remove the server's entry in Credential Manager (Windows Credentials). Windows only allows one set of credentials per server at a time."],
    ["Username in the wrong form", "Try SERVERNAME\\username (the NAS's own name), or just username, so Windows doesn't send your PC or domain name as the account's domain."],
    ["The NAS account is disabled, expired or has no permission on that share", "In DSM, check Control Panel > User & Group, and the user's permissions on the shared folder."],
    ["The password really has changed, or has a typing issue", "Sign in to DSM's web page with the same account to test it. Watch for keyboard layout and Caps Lock."],
    ["NTLM or SMB settings on an older NAS or Samba server", "Keep Windows on NTLMv2 only, and make sure the server supports NTLMv2 and SMB2/3. Windows 11 24H2 also requires SMB signing by default, which some older or third-party servers don't handle."]
  ]
}} />

One more tip: avoid typing the password on the `net use` command line, because it ends up in your command history. Use `*` and Windows will prompt for it:

```text
net use H: \\demoserver\data /user:demoserver\demouser * /persistent:yes
```

## Credits
Photo by <a href="https://unsplash.com/@johnyvino?utm_content=creditCopyText&utm_medium=referral&utm_source=unsplash">Johnyvino</a> on <a href="https://unsplash.com/photos/flat-screen-computer-monitor-turned-on-R54V69BN0MI?utm_content=creditCopyText&utm_medium=referral&utm_source=unsplash">Unsplash</a>


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Right password, but Windows says the network password is not correct (System error 86) on a Synology share? DSM Auto Block may have blocked your IP.

Windows kept rejecting the correct username and password for a Synology NAS share with "The specified network password is not correct" (System error 86). The cause was DSM's Auto Block, which had blocked the PCs' IP addresses after failed logins. How to confirm it, unblock safely, and what else causes error 86.

Tag: Microsoft

Tag: Microsoft

Synology Share Says "Network Password Is Not Correct" (System Error 86)? Check Auto Block