Policy

Alternative Port Mappings

Windows 11 25H2

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Policy overview

Key metadata and intent for this policy.

ClassComputer
CategoryNetwork > Lanman Workstation
Supported onAt least Windows Server 2025, Windows 11

Supported OS tags: Windows11, WindowsServer2025

This policy setting determines the alternative port registry mappings used by the SMB client. If you enable this policy setting, the first valid mapping will be used if the mapping's server name matches the targeted server name for connectivity. If you enable this policy setting and do not specify at least one valid mapping, or if you disable or do not configure this policy setting, then the SMB client will refer to other methods of determining alternative port usage such as with the NET USE or New-SmbMapping commands. Examples: contososa.file.core.windows.net:tcp:448 edgesrv1.corp.contoso.com:quic:450 How to modify this setting: Arrange the desired alternative port mappings in the edit box with one mapping entry per line. The format of each mapping entry specifies a server name, transport type, and port number separated by colons as done so in the example above. Note: This policy does not require a Windows reboot to take effect.

Internal name
Pol_AlternativePortMappings
Policy ID
e1633fc773f9
Elements
1

Registry values

How enabled and disabled states update the registry.

No explicit registry values are set for enabled or disabled states.

Policy elements

Inputs and configuration options exposed by this policy.

ElementTypeRegistry mappingConstraints & behavior
MultiText_AlternativePortMappings
ID MultiText_AlternativePortMappings
list
HKLM\Software\Policies\Microsoft\Windows\LanmanWorkstation\AlternativePortMappings
Type REG_MULTI_SZ
None

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