Policy
Alternative Port Mappings
Microsoft Windows
Policy overview
Key metadata and intent for this policy.
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.
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.
| Scope | Element | Type | Registry mapping | Constraints & behavior | Copy |
|---|---|---|---|---|---|
| Computer | MultiText_AlternativePortMappings ID MultiText_AlternativePortMappings | list | Path Software\Policies\Microsoft\Windows\LanmanWorkstation Value name AlternativePortMappings Type REG_MULTI_SZ | None |