Vmg8825-t50 Firmware Update |verified| Guide
A "firmware update" replaces the Kernel/RootFS and Wi-Fi blobs but usually preserves the bootloader and the calibration data (MAC addresses, RF power tables, DSL line tuning).
If the router fails to boot (Power LED solid red, no DHCP, no web interface), you have two recovery paths: vmg8825-t50 firmware update