Network isue

Question

Network isue

intusr 6

After installing 26H2 update I can't access to Win 10 network shared folder (disabled and re-enabled share but no avail), before that all worked just fine.

Error given is 0x80070043

How to fix it?

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2 answers

Your answer

Answer 1

Hello,

Thank you for posting your question on the Microsoft Windows Forum.

Since the issue started immediately after installing the 26H2 update and the error is 0x80070043 ("The network name cannot be found"), I recommend first determining whether the issue is related to SMB connectivity or name resolution.

Please test access using both:

\\ServerName\ShareName

and

\\IP_Address\ShareName

If access works by IP address but not by server name, the issue is likely related to DNS/NetBIOS name resolution rather than the shared folder itself.

You can also test SMB connectivity from an elevated Command Prompt:

net use * \\ServerName\ShareName

Additionally, review the SMB Client logs in:

Event Viewer
> Applications and Services Logs
> Microsoft
> Windows
> SMBClient
> Connectivity

Recent Windows updates may enforce stricter SMB security requirements, which can affect access to older devices, NAS appliances, or shares that rely on guest authentication.

For reference:

Microsoft SMB troubleshooting guidance https://learn.microsoft.com/troubleshoot/windows-client/networking/cannot-access-shared-folder-file-explorer
SMB access and authentication troubleshooting: https://learn.microsoft.com/en-us/troubleshoot/windows-client/networking/access-denied-access-smb-file-share

I hope this answer has brought you useful information. If so, please click on "Accept Answer" and consider upvoting it. Doing so helps other community members identify useful solutions to similar issues.

Thanks,

Maurice

intusr 6 Reputation points

2026-10-23T18:29:09.6066667+00:00

Event Viewer throws many errors like this:

Failed to establish a network connection.

Error: {Device Timeout}

The specified I/O operation on %hs was not completed before the time-out period expired.

Server name: 192.168.1.101

Server address: 192.168.1.101:445

Instance name: \Device\LanmanRedirector

Connection type: TCPIP

Port origin: The port was selected from the global registry settings.

Guidance:

This indicates a problem with the underlying network or transport, such as with TCP/IP or QUIC/UDP, and not with SMB. A firewall that blocks the TCP or UDP port listed in the Server Address field can also cause this issue.

and

Failed to establish a network connection.

Error: The QUIC connection was idle.

Server name: 192.168.1.101

Server address: 192.168.1.101:443

Instance name: \Device\LanmanRedirector

Connection type: Quic

Port origin: The port was selected from the global registry settings.

Connection ID: 0x3CC5B75A098A80A7

Client certificate thumbprint: 0x0000000000000000000000000000000000000000

Guidance:

This indicates a problem with the underlying network or transport, such as with TCP/IP or QUIC/UDP, and not with SMB. A firewall that blocks the TCP or UDP port listed in the Server Address field can also cause this issue.

DWORD is there cause this ain't 1st time with same issue, YAML and SQL fail too.

I think issue is that Win11 has bit older Comodo Internet Security while Win10 has latest version.

Answer 2

If access broke immediately after the OS update, check the SMB client security changes first. Recent Windows versions can block older or less secure share access by default, even when the share itself is still enabled.

Identify what changed on the client
- Open Command Prompt and run:
```
     net use
```
- Open PowerShell and run:
```
     Get-SmbConnection
     Get-SmbClientConfiguration
```
- Open Event Viewer > Applications and Services Logs > Microsoft > Windows > SMBClient and review the Connectivity and Security logs.
Test the share directly from Command Prompt
- Try mapping it with:
```
     net use <DeviceName>: \\<ServerName>\<ShareName>
```
- This helps confirm whether the issue is File Explorer only or SMB access in general.
If the target is an older Windows 10 device, NAS, or appliance, check for guest access blocking
- If the message mentions unauthenticated guest access being blocked, enable insecure guest logons on the client.
- Warning: this reduces security and should be used only on a trusted private network.
- Registry method:
  1. Open Registry Editor.
  2. Go to: Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\LanmanWorkstation
  3. Create DWORD (32-bit) Value named AllowInsecureGuestAuth.
  4. Set it to 1.
- Or Group Policy:
  1. Run gpedit.msc.
  2. Go to Computer Configuration > Administrative templates > Network > Lanman Workstation.
  3. Open Enable insecure guest logons and set it to Enabled.
Recheck sharing and discovery on the Windows 10 host
- Open Control Panel > Network and Internet > Network and Sharing Center > Advanced sharing settings.
- Turn on:
  - Network discovery
  - File and printer sharing
- If using a home/private network scenario, also verify the network profile is Private.
Make sure the required discovery services are running
- Open Services.
- Set these to Automatic:
  - Function Discovery Provider Host
  - Function Discovery Resource Publication
  - SSDP Discovery
  - UPnP Device Host
- Restart the PC after changing them.
If the share is visible but access is denied, verify both share and NTFS permissions on the Windows 10 folder
- On the shared folder: Properties > Sharing > Advanced Sharing > Permissions.
- Confirm the required user, or Everyone for testing, has the needed access.
- Then open Properties > Security and confirm NTFS permissions also allow access.
- A mismatch between Share and NTFS permissions can cause access failures even when sharing is enabled.
If the target only supports SMB1, temporarily enable the SMB 1.0 client to test
- Open Control Panel > Programs > Programs and Features > Turn Windows features on or off.
- Enable SMB 1.0/CIFS File Sharing Support > SMB 1.0/CIFS Client.
- Restart and test again.
- Warning: SMB1 is legacy and less secure. Use it only to confirm compatibility, then move the target device to SMB2/SMB3 if possible.
If access by name fails but IP works, enable NetBIOS over TCP/IP
- Open Control Panel > Network and Internet > Network and Sharing Center > Change adapter settings.
- Open the adapter > Properties > Internet Protocol Version 4 (TCP/IPv4) > Properties > Advanced > WINS.
- Select Enable NetBIOS over TCP/IP.
- Also open Services and make sure TCP/IP NetBIOS Helper is set to Automatic.

The most likely causes after an update are:

guest access now blocked by default
SMB signing or other SMB security enforcement changes
the target requiring SMB1
name resolution/NetBIOS failure
share or NTFS permission mismatch

References: