You cannot flash the same way via command line on x86.... you would have to dd it... I forget every so often because I do other flash based devices but as BS nicely reminded me one time:
write cannot be used for x86 images. use webflash or the .image file using dd to your physical drive. write is made for flash based devices and has a different firmware format. you may also use "writetool" to write a .image file to the current boot drive
Yeah, I am not sure why https breaks but on reboot you get an error number and it never boots...
And just for when people find this thread, if doing via command line using writetool, the syntax is:
writetool dd-wrt_x64_public_vga.image /dev/sda
in my case it is /dev/sda because I have nothing else, but be careful! I have a sata drive, so that is why it is sda but could be others depending on your device, but you are selecting the DRIVE that dd-wrt is installed on (not a specific partition)