Windows 11 KB5127936 adds IPv6 CLAT for Wi-Fi and Ethernet
Microsoft's Release Preview build 26200.9807/26300.9807 enables CLAT via netsh commands or Group Policy, with SLAAC required.
Microsoft released Windows 11 update KB5127936 to the Release Preview channel on October 16, 2026, according to forest.watch.impress.co.jp. The build, numbered 26200.9807 and 26300.9807, targets Windows 11 versions 25H2 and 26H2.
The update adds support for IPv6 CLAT on Wi-Fi and Ethernet network interfaces. CLAT is the client side of the 464XLAT IPv4/IPv6 translation method: it converts IPv4 packets to IPv6 on the device and works with network-side NAT64 to reach IPv4 services.
By default the PREF64 prefix, used to embed IPv4 addresses inside IPv6 addresses, is obtained through Router Advertisements, with a DNS lookup of ipv4only.arpa available as a fallback. CLAT requires an IPv6 address assigned via SLAAC; DHCPv6 Prefix Delegation and Windows Subsystem for Linux are not supported for now.
Users can switch CLAT on from an administrator command prompt with the command netsh interface clat set global permit=enabled pref64fromdns=enabled pref64fromra=enabled and then restart, or configure it through Group Policy.
The build also includes a customizable new right-click menu in Explorer, which is being rolled out gradually.
Quick answers
What does Windows 11 build 26200.9807 add?
It adds IPv6 CLAT support on Wi-Fi and Ethernet interfaces, plus a customizable new right-click menu in Explorer that is rolling out gradually.
How do I enable CLAT in Windows 11?
Run netsh interface clat set global permit=enabled pref64fromdns=enabled pref64fromra=enabled in an administrator command prompt and restart, or enable it via Group Policy.
Does CLAT work with WSL?
No. Windows Subsystem for Linux and DHCPv6 Prefix Delegation are not supported for now.