WSL2 localhost access is intermittent with stuck connections

[benc-uk]

Please fill out the below information:

• Your Windows build number: 10.0.18945.1001 (I am using WSL 2 mode)

• What you're doing and what's happening:

Opening a URL served via a Node.js app using localhost, from a Windows browser results in page/URL never loading. It will spin indefinitely trying to load, rather than getting an error that site/page can not be found

Hitting stop and then refresh in browser will result in page loading OK Page will continue to load OK, if you send requests to it quickly, if you wait a few seconds the problem will return and the URL and site will never load

I have verified the following:

• It only happens with Node.js, I've tried Python, .NET Core and Golang web apps with out problem
• Problem only happens with localhost, if I use the IP of eth0 and access the app that way, I get no issues
• It affects Node.js 8.x and 10.x, presumably other versions too
• I've tried with Debian 9.7 and Ubuntu 18.04 distros and both have the same problem
• It makes no difference what port I use
• It makes no difference what browser is used (Edge, Chrome, Firefox)
• It makes no difference if I use Node Express or the base http server package
• Issue doesn't happen inside WSL when accessing the app with localhost using curl or wget

This seems to be a TCP socket issue with the way WSL 2 handles the new localhost bridging out to Windows

It is trivial to reproduce. Install Node.js and run the following simple server

const http = require('http')
const requestHandler = (request, response) => {
  console.log(`### Request for ${request.url}`)
  response.end('<h1>Hello Node.js Server!</h1>')
}
const server = http.createServer(requestHandler)
server.listen(3000, '0.0.0.0', (err) => {
  if (err) return console.log('### Something bad happened', err)
  console.log(`### Server is listening on 3000`)
})

• What's wrong / what should be happening instead: HTTP request /page should instantly load

• Strace of the failing command, if applicable:
  NA

• For WSL launch issues, please [collect detailed logs] NA

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[khuongduybui]

Yes it just came back in the latest Windows update on Dev channel for me.

[illepic]

Edit: Downgrade to 1.0.3: https://github.com/microsoft/WSL/issues/9508

[ghost]

@illepic, @khuongduybui: If you're experiencing problems on 1.1.0 please see issue #9508. This issue covers 1.0.3 and before.