Watch this video before installing Openwrt on the Sophos red 15w. Problems with TFTP boot use SOLVED 

Hi my email is simpletechsolutionsbarrow@gmail.com are you booting from USB and the file type for the USB is fat32 be very carful when flashing though. It may brick the system. I got it to boot from USB and load OpenWrt fine. But when I flashed, it bricked. I think this is because the file systems were not fully wiped, or it has a hidden uboot partition. If you need any help email me if you need to send screenshots

There is also a few command that need to run before the USB command that I why I put my email, so you could send screenshots or write which cmd you are running.

@@core-computinglab it's fine I have fix the problem, the USB need to be in fat32 and not NTFS thank u

@@railloune AHH brill if you manage to fix the flashing issue please write in the comments how you did it I'm sure other people would like to know

@@xandercode How To DO ! Before doing anything format the USB stick on Fat32 (if your USB is more large than 32GB make resize under to get acess to option FAT32) and after that take the .bin and push it to the usb before execute the command on the vidéo