Name: Sierra Wireless AirCard 875 HSDPA Modem Driver
Author: Sierra Wireless

Question 1

Install fails or rolls back?

Accepted Answer

The AirCard 875 package is legacy and may be blocked by unsigned-driver or compatibility checks on newer Windows. Run the Sierra installer as administrator, use the correct 32/64-bit package, and temporarily allow unsigned drivers if needed.

Question 2

Modem not detected?

Accepted Answer

Reseat the PC Card in the slot, confirm the slot controller driver is installed, and try another compatible slot. Check Device Manager for an unknown modem/COM port; if absent, reinstall the AirCard 875 driver before opening 3G Watcher.

Question 3

Version conflicts/COM port errors?

Accepted Answer

Uninstall older Sierra Wireless Watcher/AirCard drivers and generic modem entries first, reboot, then install one matching driver package. Do not mix AirCard 875 drivers with newer Sierra modules.