WSL2 Can't connect to config correctly

[aollivier82]

I'm using Claude Code within WSL2 (Linux), and the default Claude Code config doesn't connect properly.

Here's what Claude told me it did to set it up on it's own, took me like an hour of asking it "please fix" over and over.

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Setting up Unity MCP with Claude Code on WSL2

If you're running Claude Code from WSL2 and Unity on Windows, the MCP server runs on the Windows side but Claude Code needs to reach it from WSL. Here's how to bridge the two.

1. Install the Unity package

In Unity Package Manager, add by git URL:

https://github.com/CoplayDev/unity-mcp.git?path=/MCPForUnity#main

In the Unity MCP settings, change the port to 8090 (or any free port — the default 8080 conflicts with Tailscale if you use it).

2. Install uv on Windows

The MCP server requires uv. From an admin PowerShell:

irm https://astral.sh/uv/install.ps1 | iex

3. Set up port forwarding from WSL to Windows

WSL2 runs in a separate network namespace, so you need to forward the MCP port. From an admin PowerShell:

netsh interface portproxy add v4tov4 listenport=8090 listenaddress=0.0.0.0 connectport=8090 connectaddress=127.0.0.1

Then add a firewall rule to allow it:

New-NetFirewallRule -DisplayName "Unity MCP Server" -Direction Inbound -LocalPort 8090 -Protocol TCP -Action Allow

4. Find your WSL host IP

From inside WSL, run:

cat /etc/resolv.conf | grep nameserver | awk '{print $2}'

This prints the Windows host IP as seen from WSL (e.g. 172.21.48.1). It's a private address that varies per machine.

5. Add the MCP server to Claude Code

From WSL, using the IP from step 4:

claude mcp add --transport http UnityMCP http://<YOUR_WSL_HOST_IP>:8090/mcp

For example:

claude mcp add --transport http UnityMCP http://172.21.48.1:8090/mcp

Note: this uses HTTP transport, not stdio — since the server is running on the Windows side.

6. Verify

Start Unity, then start Claude Code. You should see UnityMCP listed as a connected MCP server. You can test it by asking Claude to get your scene info.

Notes

• If you restart your machine, the WSL host IP may change. Re-run step 4 and update the MCP config if needed.
• The port proxy persists across reboots. To remove it later: netsh interface portproxy delete v4tov4 listenport=8090 listenaddress=0.0.0.0
• If the connection fails, make sure Unity is running and the MCP server is started (check the Unity MCP panel).

[dsarno]

Thanks for the detailed writeup — this is a great reference for WSL2 users!

We actually have an Allow LAN Bind (HTTP Local) setting in Advanced Settings that handles this. There are two approaches depending on your security preferences:

Option A: Simple (Allow LAN Bind)

If you're on a trusted/home network, check Allow LAN Bind (HTTP Local) in the MCP for Unity Advanced Settings. This binds the server to all interfaces (0.0.0.0) so WSL2 can reach it directly — no port forwarding needed.

1. In the MCP for Unity window, set transport to HTTP Local
2. In Advanced Settings, check Allow LAN Bind (HTTP Local)
3. Start the server
4. In WSL2, find your host IP: cat /etc/resolv.conf | grep nameserver | awk '{print $2}'
5. Configure Claude Code: claude mcp add --transport http UnityMCP http://<HOST_IP>:8090/mcp

⚠️ Note: This listens on all network interfaces, meaning other devices on your LAN could potentially reach the server. Windows Firewall will typically block unsolicited inbound connections unless you add a rule, but be aware of the exposure.

Option B: Secure (localhost + port forwarding)

If you're on an untrusted network, keep the server bound to localhost and use port forwarding. More setup, but the server is never exposed to your local network.

1. In the MCP for Unity window, set transport to HTTP Local (leave Allow LAN Bind unchecked)
2. Change the port if needed (e.g. http://localhost:8090 to avoid conflicts)
3. From an admin PowerShell, set up port forwarding:

   netsh interface portproxy add v4tov4 listenport=8090 listenaddress=0.0.0.0 connectport=8090 connectaddress=127.0.0.1
   

4. Add a firewall rule:

   New-NetFirewallRule -DisplayName "Unity MCP Server" -Direction Inbound -LocalPort 8090 -Protocol TCP -Action Allow
   

5. In WSL2, find your host IP: cat /etc/resolv.conf | grep nameserver | awk '{print $2}'
6. Configure Claude Code: claude mcp add --transport http UnityMCP http://<HOST_IP>:8090/mcp

Tip: The WSL host IP can change after a reboot. Re-run the host IP step and update the MCP config if the connection stops working. The port proxy persists across reboots — to remove it later: netsh interface portproxy delete v4tov4 listenport=8090 listenaddress=0.0.0.0

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Both options require HTTP transport (not stdio) since Claude Code in WSL2 can't launch a Windows uvx process directly.

[dsarno]

Thanks for reporting this @aollivier82! We've added a WSL2 setup guide to the wiki based on the workaround documented here: https://github.com/CoplayDev/unity-mcp/wiki/3.-Common-Setup-Problems#wsl2-connecting-claude-code-linux-to-unity-windows