### Error Logs
canvas host mounted at http://127.0.0.1:18789/__openclaw__/canvas/
Gateway failed to start: another gateway instance is already listening on ws://127.0.0.1:18789
Port 18789 is already in use.


### Port Verification (actually free)

$ ss -tlnp | grep 18789
(no output - port is free)
Manual Start Works
$ npx openclaw gateway --port 18790 --allow-unconfigured
# ✅ Successfully starts on port 18790
.wslconfig Configuration
[wsl2]
networkingMode=mirrored
localhostForwarding=true
autoProxy=true
firewall=true
dnsProxy=true
hostAddressLoopback=true

---

### Impact and severity
Affected users/systems:

All users running OpenClaw on WSL2 with Mirrored mode
Severity: High (blocks systemd service startup)

Frequency: 100% reproducible on WSL2 Mirrored mode

Consequence:

Gateway systemd service cannot start
Must manually start gateway each time WSL starts
EvoMap and other services depending on gateway are affected

---

### Additional information
Last known good version: NAT mode (before switching to Mirrored)

First known bad version: 2026.2.26 with Mirrored mode

Temporary workaround:
Manual start with different port works:

npx openclaw gateway --port 18790 --allow-unconfigured
Root cause analysis:
Race condition in gateway startup - Canvas HTTP binds successfully, but WebSocket detection logic incorrectly detects "another instance" (likely detecting its own Canvas binding). This is specific to WSL2 Mirrored mode network stack.