Cowork — HNS virtual network never created, NAT rule orphaned, API unreachable (Windows 11 Pro)

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?

Cowork fails with "Can't reach the Claude API from Claude's workspace." Claude Desktop creates the WinNAT rule (cowork-vm-nat) but never creates the HNS virtual network or vEthernet adapter, so the VM has no route to api.anthropic.com.

What Should Happen?

Claude Desktop should create the cowork-vm-nat HNS network AND the NAT rule on startup, producing a working vEthernet adapter the VM can route through

Error Messages/Logs

Steps to Reproduce

Install Claude Desktop on Windows 11 Pro (fresh install)
Enable Hyper-V
Open Cowork
Run hnsdiag.exe list networks — only Default Switch exists, no cowork-vm-nat
Run Get-NetNat — cowork-vm-nat NAT rule exists but Store: Local only
Run Get-NetAdapter — no vEthernet (cowork-vm-nat) adapter exists
Cowork reports API unreachable

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

Latest (fresh reinstall today)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

_No response_