---
summary: "Troubleshoot WSL2 Gateway + Windows Chrome remote CDP in layers"
read_when:
  - Running OpenClaw Gateway in WSL2 while Chrome lives on Windows
  - Seeing overlapping browser/control-ui errors across WSL2 and Windows
  - Deciding between host-local Chrome MCP and raw remote CDP in split-host setups
title: "WSL2 + Windows + remote Chrome CDP troubleshooting"
---

In the common split-host setup, OpenClaw Gateway runs inside WSL2, Chrome runs
on Windows, and browser control must cross the WSL2/Windows boundary. Several
independent problems can surface at once (see
[issue #39369](https://github.com/openclaw/openclaw/issues/39369)): CDP
transport, Control UI origin security, and token/pairing can each fail on
their own while producing similar-looking errors. Work through the layers
below in order instead of guessing which one is broken.

## Choose the right browser mode first

### Option 1: raw remote CDP from WSL2 to Windows

Use a remote browser profile pointing from WSL2 to a Windows Chrome CDP
endpoint. Choose this when the Gateway stays inside WSL2, Chrome runs on
Windows, and browser control needs to cross the WSL2/Windows boundary.

### Option 2: host-local Chrome MCP

Use the `existing-session` driver (`user` profile) only when the Gateway runs
on the same host as Chrome, you want the local signed-in browser state, you do
not need cross-host browser transport, and you do not need `responsebody`,
PDF export, download interception, or batch actions (Chrome MCP profiles do
not support these).

For WSL2 Gateway + Windows Chrome, use raw remote CDP. Chrome MCP is
host-local, not a WSL2-to-Windows bridge.

## Working architecture

- WSL2 runs the Gateway on `127.0.0.1:18789`
- Windows opens the Control UI in a normal browser at `http://127.0.0.1:18789/`
- Windows Chrome exposes a CDP endpoint on port `9222`
- WSL2 can reach that Windows CDP endpoint
- OpenClaw points a browser profile at the address reachable from WSL2

## Critical rule for the Control UI

When the UI is opened from Windows, use Windows localhost unless you have a
deliberate HTTPS setup:

```text
http://127.0.0.1:18789/
```

Do not default to a LAN IP. Plain HTTP on a LAN or tailnet address can
trigger insecure-origin/device-auth behavior unrelated to CDP itself. See
[Control UI](/web/control-ui).

## Validate in layers

Work top to bottom; do not skip ahead. Fixing one layer can still leave a
different error visible from a layer further down.

### Layer 1: verify Chrome is serving CDP on Windows

```powershell
chrome.exe --remote-debugging-port=9222 --user-data-dir="$env:LOCALAPPDATA\OpenClaw\ChromeCDP"
```

Chrome 136 and later ignore remote-debugging command-line switches for the
default Chrome data directory. Use a separate, non-default data directory as
shown above. See Chrome's
[remote-debugging security change](https://developer.chrome.com/blog/remote-debugging-port).
This does not make the normal signed-in Chrome profile remotely controllable.

From Windows, verify Chrome itself first:

```powershell
curl.exe http://127.0.0.1:9222/json/version
curl.exe http://127.0.0.1:9222/json/list
```

If this fails, diagnose the Windows listeners below. OpenClaw is not the
problem yet.

#### Diagnose IPv4 and IPv6 before changing portproxy

Chromium tries to bind remote debugging to `127.0.0.1` first and falls back to
`[::1]` only if the IPv4 bind fails. A persistent `v4tov4` rule listening on
`127.0.0.1:9222` can occupy that endpoint before Chrome starts. Chrome then
falls back to `[::1]:9222`, while the old rule forwards IPv4 traffic back to
its own listener and returns an empty reply.

Check the actual listeners and proxy rules from Windows instead of inferring
them from the Chrome version:

```powershell
netstat -ano | findstr :9222
netsh interface portproxy show all
curl.exe http://127.0.0.1:9222/json/version
curl.exe http://[::1]:9222/json/version
```

Use `tasklist /fi "PID eq <PID>"` for each PID from `netstat`.

- If `chrome.exe` answers on `127.0.0.1`, remove any portproxy rule that also
  listens on `127.0.0.1:9222`. Forward only the WSL2-reachable Windows adapter
  address to `127.0.0.1`.
- If `chrome.exe` answers only on `[::1]`, point the WSL2-reachable listener at
  `::1` with `v4tov6` instead of forwarding to an unused IPv4 address:

  ```powershell
  netsh interface portproxy add v4tov6 listenaddress=WINDOWS_HOST_OR_IP listenport=9222 connectaddress=::1 connectport=9222
  ```

Bind the listener to the adapter address WSL2 needs. Do not expose the CDP
port on `0.0.0.0`, a LAN address, or a tailnet address: CDP grants control of
the browser session.

### Layer 2: verify WSL2 can reach that Windows endpoint

From WSL2, test the exact address you plan to use in `cdpUrl`:

```bash
curl http://WINDOWS_HOST_OR_IP:9222/json/version
curl http://WINDOWS_HOST_OR_IP:9222/json/list
```

Good result:

- `/json/version` returns JSON with Browser / Protocol-Version metadata
- `/json/list` returns JSON (an empty array is fine if no pages are open)

If this fails, Windows is not exposing the port to WSL2 yet, the address is
wrong for the WSL2 side, or firewall/port-forwarding/proxying is missing. Fix
that before touching OpenClaw config.

### Layer 3: configure the correct browser profile

Point OpenClaw at the address reachable from WSL2:

```json5
{
  browser: {
    enabled: true,
    defaultProfile: "remote",
    profiles: {
      remote: {
        cdpUrl: "http://WINDOWS_HOST_OR_IP:9222",
        attachOnly: true,
      },
    },
  },
}
```

Notes:

- use the WSL2-reachable address, not whatever only works on Windows
- keep `attachOnly: true` for externally managed browsers
- `cdpUrl` can be `http://`, `https://`, `ws://`, or `wss://`
- use HTTP(S) when you want OpenClaw to discover `/json/version`
- use WS(S) only when the browser provider gives you a direct DevTools
  socket URL
- test the same URL with `curl` before expecting OpenClaw to succeed

### Layer 4: verify the Control UI layer separately

Open `http://127.0.0.1:18789/` from Windows, then verify:

- the page origin matches what `gateway.controlUi.allowedOrigins` expects
- token auth or pairing is configured correctly
- you are not debugging a Control UI auth problem as if it were a browser
  problem

Helpful page: [Control UI](/web/control-ui).

### Layer 5: verify end-to-end browser control

From WSL2:

```bash
openclaw browser --browser-profile remote open https://example.com
openclaw browser --browser-profile remote tabs
```

Good result:

- the tab opens in Windows Chrome
- `browser tabs` returns the target
- later actions (`snapshot`, `screenshot`, `navigate`) work from the same
  profile

## Common misleading errors

| Message                                                                                 | Meaning                                                                                                                                                                           |
| --------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `control-ui-insecure-auth`                                                              | UI origin/secure-context problem, not a CDP transport problem                                                                                                                     |
| `token_missing`                                                                         | auth configuration problem                                                                                                                                                        |
| `pairing required`                                                                      | device approval problem                                                                                                                                                           |
| `Remote CDP for profile "remote" is not reachable`                                      | WSL2 cannot reach the configured `cdpUrl`                                                                                                                                         |
| empty CDP reply / `other side closed` through a portproxy                               | Windows listener mismatch or a self-loop; inspect both loopback families and `netsh interface portproxy show all`                                                                 |
| `Browser attachOnly is enabled and CDP websocket for profile "remote" is not reachable` | the HTTP endpoint answered, but the DevTools WebSocket could not be opened                                                                                                        |
| stale viewport / dark-mode / locale / offline overrides after a remote session          | run `openclaw browser --browser-profile remote stop` to close the session and release the cached Playwright/CDP connection without restarting the Gateway or the external browser |
| timeout during CDP reachability                                                         | usually still CDP reachability, or a slow/unreachable remote endpoint                                                                                                             |
| `Playwright page enumeration timed out after 3000ms`                                    | the remote CDP connected, but its persistent tab read stalled                                                                                                                     |
| `No Chrome tabs found for profile="user"`                                               | local Chrome MCP profile selected where no host-local tabs are available                                                                                                          |

## Fast triage checklist

1. Windows: which of `127.0.0.1` or `[::1]` answers on `/json/version`, and
   does that listener belong to `chrome.exe`?
2. WSL2: does `curl http://WINDOWS_HOST_OR_IP:9222/json/version` work?
3. OpenClaw config: does `browser.profiles.<name>.cdpUrl` use that exact
   WSL2-reachable address?
4. Control UI: are you opening `http://127.0.0.1:18789/` instead of a LAN IP?
5. Are you trying to use `existing-session` across WSL2 and Windows instead
   of raw remote CDP?

Verify the Windows Chrome endpoint locally first, verify the same endpoint
from WSL2 second, and only then debug OpenClaw config or Control UI auth.

## Related

- [Browser](/tools/browser)
- [Browser login](/tools/browser-login)
- [Browser Linux troubleshooting](/tools/browser-linux-troubleshooting)
