Update Docker documentation to include instructions for connecting COM ports on Windows 11. Added detailed steps for installing USB bridge, binding devices, and configuring Docker to use Linux device names.

docs/DOCKER.md

@@ -73,7 +73,6 @@ The `docker-compose.yml` file maps the following directories:
 ### Serial Port Access
 
 **⚠️ Important: Docker Desktop on macOS does NOT support serial device passthrough.**
-
 If you're using a serial connection, you have several options:
 
 **Option 1: Use TCP Connection (Recommended for macOS)**
@@ -108,6 +107,8 @@ network_mode: host
 ```
 **Note**: Host network mode gives the container full access to the host network, which has security implications.
 
+**Windows 11 (Docker Desktop / WSL2):** See [Connecting COM Ports to Docker on Windows 11](#connecting-com-ports-to-docker-on-windows-11) below.
+
 ### Web Viewer Port
 
 If you enable the web viewer, uncomment and adjust the `ports` section:
@@ -278,12 +279,15 @@ If you see `[Errno 13] Permission denied` when accessing serial devices:
 
 ### Serial Port Not Found
 
-1. **Check device exists**:
+1. **Windows: "No such file or directory: 'COM3'"**  
+   Docker on Windows (WSL2) cannot see Windows COM ports. See [Connecting COM Ports to Docker on Windows 11](#connecting-com-ports-to-docker-on-windows-11) above.
+
+2. **Check device exists** (Linux):
    ```bash
    ls -l /dev/ttyUSB0  # or your device
    ```
 
-2. **Use host network mode** if device mapping doesn't work:
+3. **Use host network mode** if device mapping doesn't work:
    ```yaml
    network_mode: host
    ```
@@ -466,6 +470,68 @@ docker-compose up -d
 
 5. **Web viewer**: If enabled, ensure it's only accessible on trusted networks or use a reverse proxy with authentication
 
+## Connecting COM Ports to Docker on Windows 11 {#connecting-com-ports-to-docker-on-windows-11}
+
+On Windows 11, Docker runs inside a Linux VM (WSL2). Linux does not see Windows COM ports by default, so the bot may fail with:
+
+```
+Connection failed: [Errno 2] could not open port COM3: [Errno 2] No such file or directory: 'COM3'
+```
+
+Even if the port works in Windows (e.g. in Device Manager or in [app.meshcore.nz](https://app.meshcore.nz)), you must **pass the USB device from Windows into WSL** so the container can use it.
+
+**1. Install the USB bridge**
+
+Open **PowerShell as Administrator** and run:
+
+```powershell
+winget install --id Microsoft.usbipd-win
+```
+
+Restart your computer if prompted.
+
+**2. Identify and share the radio**
+
+With the radio plugged in, in PowerShell:
+
+- **Find the device**: Run `usbipd list`. Note the **BUSID** for your radio (e.g. `2-3`).
+- **Bind it**: Run `usbipd bind --busid <YOUR-BUSID>`.
+- **Attach to WSL**: Run `usbipd attach --wsl --busid <YOUR-BUSID>`.
+
+**Important:** Close any app that is using the serial port (e.g. the [app.meshcore.nz](https://app.meshcore.nz) browser tab) before binding. Only one process can own the port at a time.
+
+**3. Use the Linux device name in Docker**
+
+After attaching, the device in WSL is no longer `COM3`. It will typically appear as `/dev/ttyUSB0`. To confirm, inside WSL run:
+
+```bash
+ls /dev/tty*
+```
+
+**4. Update Docker and config**
+
+In `docker-compose.yml`, add (or adjust) the device mapping:
+
+```yaml
+devices:
+  - "/dev/ttyUSB0:/dev/ttyUSB0"
+```
+
+In `config.ini`, set the serial port to the Linux device:
+
+```ini
+[Connection]
+connection_type = serial
+serial_port = /dev/ttyUSB0
+```
+
+**Notes:**
+
+- Bind/attach is **not persistent**. After a reboot or unplugging the radio, run `usbipd bind` and `usbipd attach --wsl` again (or use a script).
+- To attach to the Docker Desktop distro specifically:  
+  `usbipd attach --wsl --busid <BUSID> --distribution docker-desktop`  
+  (Use `usbipd --help` to see your exact distribution name.)
+
 ## Additional Resources
 
 - [Docker Documentation](https://docs.docker.com/)