Not working in dev containers

[collimarco]

Which version line?

v2 — current (@modelcontextprotocol/inspector@latest)

Which client?

Web

Inspector version

2.1.0

Node version

24.16.0

Operating system (and browser, for the web client)

macOS 15.7, Safari or Chrome

Transport

stdio

MCP server under inspection

Any server under inspection, even a simple npx @modelcontextprotocol/inspector without args fails

Steps to reproduce

1. Create a dev container in VS Code:

{
"name": "my-mcp-dev",
"image": "mcr.microsoft.com/devcontainers/typescript-node:4-24-trixie",
"forwardPorts": [6274, 6275, 6277]
}

2. Run npx @modelcontextprotocol/inspector inside the container terminal
3. Everything seems correct in terminal (MCP Inspector Web is up and running at...) but the browser keeps loading the page without any response from server (even a page refresh doesn't work)

Expected behavior

Inspector is opened correctly in the browser.

Actual behavior

Inspector in the browser never loads... the browser is stuck forever while loading http://localhost:6274...

Logs, errors, or screenshots

No response

Already prototyped a fix?

No response

Before you submit

• I searched existing issues and this is not a duplicate.
• This is not a security vulnerability report (those go through the private advisory process).