While there is no official direct download link for a standalone "Mkey Router Modem V849" firmware, typically refers to a USB Dongle used for unlocking mobile modems.
Research the Seller:
NVM Management: Reading and writing Non-Volatile Memory (NVM) to fix WiFi, RF, or charging issues. mkey router modem v849 link download
The software supports a vast array of devices, enabling features that standard consumer firmware often restricts: While there is no official direct download link
http://dl.mkeynetworks.com/v849/driver_firmware/ Seller’s support (email or message)