Cowork/Windows - Can't reach the Claude API from Claude's workspace on fresh install — no VPN on

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?

When launching Cowork on Windows, I get:

"Failed to start Claude's workspace — Can't reach the Claude API from Claude's workspace. Restarting Claude or reconnecting to your network sometimes resolves this."

Normal Claude Desktop chat works fine. Only Cowork fails to connect.
Environment

OS: Windows 11 [Home/Pro — whichever you have] — [your build number, find it via Win + R → winver]
Claude Desktop version: [check Help → About in Claude Desktop]
Network: Private Wi-Fi, no VPN or proxy active
Location: Luxembourg

Steps to reproduce

Open Claude Desktop
Navigate to Cowork
Error appears immediately

What I've tried

Restarted Claude Desktop
Restarted Windows
Confirmed internet connection works (regular Claude chat is fine)

What Should Happen?

Cowork should start successfully and connect to the Claude API without errors on Windows, allowing me to use the Cowork workspace as intended. The VM should be able to reach api.anthropic.com over my normal internet connection without requiring any manual network configuration.

Error Messages/Logs

Failed to start Claude's workspace
Can't reach the Claude API from Claude's workspace.
Restarting Claude or reconnecting to your network sometimes resolves this.

Steps to Reproduce

Install Claude Desktop on Windows 11 (latest version)
Confirm normal Claude chat works (internet connection is fine)
No VPN or proxy active, connected via private Wi-Fi
Navigate to Cowork from Claude Desktop
Cowork attempts to start the workspace
Error appears: "Failed to start Claude's workspace — Can't reach the Claude API from Claude's workspace"
Restarting Claude Desktop and rebooting Windows does not resolve the issue

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

N/A — Using Cowork via Claude Desktop v1.1.3189 (1b7b58), not Claude Code CLI

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Other

Additional Information

_No response_