[BUG] Cowork plugins not working - plugins.claude.ai DNS NXDOMAIN (Windows, Max plan)

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 plugin marketplace and plugin installation do not work on Windows. The root cause is that plugins.claude.ai does not resolve via DNS (returns NXDOMAIN).

DNS test from Cowork VM:

$ nslookup plugins.claude.ai
Server: 172.16.10.1
** server can't find plugins.claude.ai: NXDOMAIN

Other Anthropic domains resolve fine:

• claude.ai → 160.79.104.10 ✅
• api.anthropic.com → 160.79.104.10 ✅
• plugins.claude.ai → NXDOMAIN ❌

Also tested from browser: navigating to https://plugins.claude.ai shows an error page (DNS resolution failure).

This affects both the plugin marketplace UI (stuck on skeleton/placeholder) and plugin installation via Cowork.

Environment:

• Plan: Max
• OS: Windows
• All capabilities enabled (Code execution, Network egress, All domains)
• Skills and Connectors sections accessible in Settings

Related issues: #28853, #26951, #26450

What Should Happen?

plugins.claude.ai should resolve via DNS and be accessible. The Cowork plugin marketplace should load and display available plugins. Users should be able to browse and install plugins from the marketplace.

Error Messages/Logs

$ nslookup plugins.claude.ai
Server:    172.16.10.1
Address:   172.16.10.1#53

** server can't find plugins.claude.ai: NXDOMAIN

$ ping -c 2 plugins.claude.ai
ping: plugins.claude.ai: Name or service not known

Browser navigation to https://plugins.claude.ai returns ERR_NAME_NOT_RESOLVED

Steps to Reproduce

1. Open Claude Desktop (Cowork mode) on Windows with a Max plan
2. Try to access the plugin marketplace / browse plugins
3. Observe that the marketplace fails to load (skeleton placeholders remain indefinitely)
4. From Cowork VM terminal, run: nslookup plugins.claude.ai — returns NXDOMAIN
5. From browser, navigate to https://plugins.claude.ai — shows DNS error page
6. Compare with nslookup claude.ai which resolves correctly to 160.79.104.10

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

Claude Desktop (Cowork) - latest version as of March 2, 2026

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

This appears to be a server-side infrastructure issue on Anthropic's end — the plugins.claude.ai DNS record does not exist or is not publicly accessible. All other Anthropic domains (claude.ai, api.anthropic.com) resolve correctly.

User account settings are all correct:

• Max plan (active subscription)
• Code execution: enabled
• Network egress: enabled
• Domain allowlist: All domains
• Skills section accessible via Settings > Capabilities > Customize

Multiple other users have reported the same issue: #28853, #26951, #26450, #29047, #28972.