Troubleshooting WSL + localhost:3000 'connection refused' issue

Just spent an hour trying to figure out why the browser wouldn't open localhost:3000 (served by Webpack/create-react-app in WSL2).

Normally, a server running in WSL should be accessible from the Windows (host) machine without any issues.

My troubleshooting steps, roughly:

• check /windows/system32/drivers/etc/hosts file --nothing special here...
• check Windows firewall rules, just in case
• shut down WSL VM with wsl --shutdown command and restart it
• run another app in WSL using a different port -- hmm, this works...
• change the port of the app in question in Webpack config: PORT=3006 react-scripts start -- also works... so the problem is in the specific port!
• see if some process is holding the port 3000 in Linux: ss -tulpn
• check if a process is holding the port in Windows: netstat -ano | findstr :3000 or Resource Monitor -> Network tab -> Listening ports -- aha! there is one!
• find the process name by PID in the Task Manager -> Services

Turns out, the port was taken by IP Helper service (iphlpsvc).

I could not find a way to reconfigure it, and some quick research showed that it wasn't a critical service (at least in my case), so I just disabled it in the Services.

Comments

[Sebbe Selvig]

I found that changing the port helps, each time I shutdown my webpack-dev-server and my laptop, the next day the port is "dead" again.

Using wsl --shutdown works, so starting my day with that command solved any issues, quite annoying.

The port issue is not a problem for other appliances as docker containers.

[Ciprian]

I signed up to dev.to only to like this comment :)

I was tired of restarting my PC to get Nuxtjs working and couldn't find any other fix to this bug.

You Sir have saved my life, haha.

[Alexandria Cornwall]

Just a quick heads-up: Disabling iphlpsvc can break TCP forwarding from WSL 2. You might use this feature, for example, if you're trying to debug locally from your phone: github.com/microsoft/WSL/issues/4150

I don't really have a solution other than disabling iphlpsvc, starting up node / yarn, then re-enabling iphlpsvc (or just choosing a different port to start on).

[Maxim Mazurok]

This command causes the port to get hogged by IP Helper:

iex "netsh interface portproxy add v4tov4 listenport=$port listenaddress=$addr connectport=$port connectaddress=$remoteport";

And this command can un-hog it:

$addr='0.0.0.0';
$port=3000;
iex "netsh interface portproxy delete v4tov4 listenport=$port listenaddress=$addr";

But you do loose port forwarding from WSL to Windows in this case.

Also, in my case I was able to create server on the same port, and Chrome could open site ok, but Chrome controlled by Cypress coudln't open it, was timing out. Which is weird.

[Alex Antsiferov]

@acornwall Thanks for mentioning this! Indeed, IP Helper service may be needed at some point, so it's definitely not the bulletproof solution :)

[Mersad Ajanovic]

About time you get a mac :D

[Alex Antsiferov]

Or just switch to Ubuntu completely :)

[Mersad Ajanovic]

Well, I wouldn't mind Ubuntu if it weren't for the lack of a proper ecosystem and added os maintenance. I used windows and ubuntu for years but it just takes too much time to care for the system. Most of the time I found myself with one issue or another that is not related to actual work. On mac, I had more peace of mind and focus on work.

[perseon]

linux needs the least maintenance of the 3 OSes. I use it on my workstation and it never got in my way. macos is just an interface that gets in the way of proper programmers.