Port missing

Do not add a legacy COM port manually; connect the USB-serial device, identify its hardware ID, and install an ARM64-compatible driver from that device or chipset manufacturer.

The Surface driver package updates the Surface’s own hardware and firmware. It does not contain drivers for every USB-serial modem or adapter. Because the Surface Pro 11 with Snapdragon runs Windows on ARM, peripherals that require drivers must have drivers designed for ARM-based Windows; application emulation does not substitute for a compatible device driver.^1^

Identify the required peripheral driver

Since the Surface drivers and firmware are already current, proceed with the attached device:

1. Connect the USB-serial modem directly to the Surface, temporarily avoiding a dock or hub.
2. Open Device Manager.
3. Look under:
   • Other devices
   • Universal Serial Bus devices
   • Universal Serial Bus controllers
   • Modems
4. Right-click the device that appears or changes when the modem is connected, then select Properties → Details.
5. From Property, select Hardware Ids.
6. Record the first value, normally resembling:

      USB\VID_1234&PID_5678
   

   Windows obtains these vendor and product identifiers from the USB device and uses them to find a matching INF driver package.^2^
7. Use the VID/PID, modem model, or USB-serial chipset name to obtain a driver explicitly supporting Windows 11 ARM64 from the device or chipset manufacturer. Do not use Have Disk with an x86- or x64-only driver.

A closely matching Surface Snapdragon case likewise required checking with the peripheral manufacturer whether its driver specifically supports Snapdragon X on Windows 11.^3^

When no separate driver should be necessary

If the modem identifies itself as a standard USB Communications Device Class device with the expected class and subclass identifiers, Windows should automatically load its built-in Usbser.sys driver through Usbser.inf. Microsoft states that no separate download is required for a correctly identified compatible device; if Windows does not install it, the device manufacturer should be contacted.^4^

After successful driver installation, Device Manager should show something similar to:

Ports (COM & LPT)
  USB Serial Port (COM3)

The Ports (COM & LPT) section may be absent until a serial driver registers an actual COM-port interface. It is not a feature that must be separately activated.^5^

If the device remains unidentified

Check Properties → General for the status:

• Code 28 generally means the USB device enumerated, but Windows could not find a matching INF driver.
• Code 43 or an ID such as USB\UNKNOWN indicates that USB enumeration itself failed, which can involve the device, cable, adapter, or descriptor exchange.^6^

If the manufacturer offers no Windows 11 ARM64 driver and the device does not use the compatible in-box USB serial class, the practical resolution is an ARM64-supported USB-serial modem or adapter. The legacy-hardware wizard’s filename/directory error does not identify a missing file from the Surface MSI, and manually creating a generic port will not supply the peripheral-specific driver.

References

1. Using software and peripherals on Surface ARM-based devices
2. Enumeration of USB composite devices
3. I cnnot get USB devices or drivers to work on my surface pro - Microsoft Q&A
4. USB serial driver (Usbser.sys)
5. GUID_DEVINTERFACE_COMPORT
6. Case Study: Troubleshooting an unknown USB device by using ETW and Netmon