Windows Copilot App resets connection to valid Streamable HTTP MCP server

Greetings. I cannot add the dbatools MCP server at https://mcp.dbatools.io

This MCP Server works in Claude Code and Codex.

### Environment

- GitHub Copilot App: 1.1.4
- Bundled Copilot CLI: 1.0.78-2
- Platform: Windows x86_64
- MCP transport: Streamable HTTP
- Endpoint: `https://mcp.dbatools.io/`

### Configuration

```json
{
"mcpServers": {
"dbatools": {
"tools": ["*"],
"type": "http",
"url": "https://mcp.dbatools.io/"
}
}
}
```

### Problem

The Copilot App cannot initialize this MCP server. Its log reports:

```text
reqwest::Error {
kind: Request,
url: "https://mcp.dbatools.io/",
source: hyper_util::client::legacy::Error(
Connect,
Os {
code: 10054,
message: "An existing connection was forcibly closed by the remote host."
}
)
}
```

The UI reports:

```text
failed to initialize MCP client
Client error: error sending request for url (https://mcp.dbatools.io/)
```

### Expected behavior

Copilot connects using Streamable HTTP and discovers the server’s three tools.

### Independent verification

The same endpoint works successfully with both **Claude Code** and **OpenAI Codex** using Streamable HTTP.

Additionally, from the same Windows machine:

- `GET https://mcp.dbatools.io/health` returns HTTP 200.
- A valid MCP `initialize` POST returns HTTP 200 with `Content-Type: text/event-stream` and a valid initialization result.
- TLS/HTTPS requests succeed against each of the hostname’s three Cloudflare IPv4 addresses.
- A browser-style GET intentionally redirects to the documentation, but MCP POST requests do not redirect.

### Reproduction

1. Open Settings → MCP servers.
2. Add `https://mcp.dbatools.io/` using HTTP transport.
3. Enable the server.
4. Observe the connection error.
5. The log records Windows socket error 10054 during Copilot’s `reqwest` connection.

Could you confirm whether the Windows MCP HTTP client has a TLS compatibility issue with this Cloudflare-hosted endpoint, or whether Copilot requires additional server-side TLS behavior not required by Claude Code or Codex?