[BUG] Cowork plugin install fails on Windows 11 Pro — 172.16.0.0/24 NAT rule cannot be created despite empty Get-NetNat

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

Environment:

Windows 11 Pro
Dell laptop
Claude Desktop latest version (February 2026)
Paid Claude subscription

Problem:
Cowork itself launches and works fine, but installing any plugin (specifically the Marketing plugin) fails. After investigating, the root cause is that Cowork's VM cannot create its required NAT rule.
Diagnosis steps completed:

BIOS virtualization: Intel VT-x and VT-d both ON
Hyper-V Windows feature: Enabled
bcdedit hypervisorlaunchtype: Auto
systeminfo confirms: "A hypervisor has been detected"
Cowork virtual adapter exists: vEthernet (cowork-vm-vnet) — Status: Up, 10 Gbps
VM IP address: 172.16.0.1/24 (confirmed via Get-NetIPAddress)
Get-NetNat returns: empty (no NAT rules exist)
Attempting New-NetNat -Name "cowork-vm-nat" -InternalIPInterfaceAddressPrefix "172.16.0.0/24" fails with Windows System Error 52 (duplicate name) every time, even after stopping and restarting the HNS service
HNSPolicy.json does not exist on this machine
Get-VMSwitch shows cowork-vm-vnet as Internal switch owning 172.16.0.1 — this appears to be what blocks the NAT rule from being created on the same range
Successfully created NAT on 192.168.100.0/24 as a test — confirmed working, but Cowork does not use this range

Root cause (suspected):
Cowork hardcodes 172.16.0.0/24 for its VM NAT but its own virtual switch (cowork-vm-vnet) claims that IP first, preventing the NAT rule from ever being created. Get-NetNat returns empty so there is no visible conflict, but Windows still rejects the NAT creation with error 52.
Impact:
Plugin marketplace fails to load. No plugins can be installed. Cowork is partially functional (tasks work) but plugins are completely inaccessible.
Request:
Please fix Cowork's network setup logic on Windows to either: (a) create the NAT rule before or alongside the virtual switch, or (b) detect when 172.16.0.0/24 is unavailable and fall back to an alternative range automatically.

What Should Happen?

Claude desktop cowork not ...working

Error Messages/Logs

Virtualization is not enabled
Claude's workspace requires hardware virtualization (Hyper-V). Enable virtualization in your computer's BIOS/UEFI settings, then restart.

Steps to Reproduce

open claude desktop and then cowork

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

Claude 1.1.3918 (a4b368) 2026-02-20T23:13:32.000Z

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

_No response_