Sierra modem configuration
If your Sierra modem (7304, 7354) has been connected to a Windows 10 computer and you are planning to downgrade to Windows 7, you might need to re-configure the modem for it to work.
Download the tool at the bottom of this site and follow the below instructions to re-configure your modem.
The windows driver changes the configuration to mbim when connected to win10. The solution is:
1. Connect the modem to win10
2. Run the attached SetUSBComp tool
3. Once the device is detected by the tool, select win7 option and set.
4. Power off/on the module to see the change back to QMI mode.
To avoid this update, you can also disable that feature on the driver. When you run the driver installer, while reinstalling, the following line must be added to configuration.ini prior to installation on Windows 8 or higher: DisableUsbCompAutoUpdate=1
Another option is that you can also search your registry for that value and change it on the fly. You can also uninstall swiservice, which is the service that performs the automatic switch. If you install the drivers manually, without SwiService, the automatic update is also avoided.