Last Update: 06-20-2023
dd-wrt.v24-K3_AC_ARM_STD_128K.tar.xz (21.8 MB)
R6400-V1.0.0.26_1.0.14.tar.xz (27.5 MB)
Select dd-wrt.v24-K3_AC_ARM_STD_128K.bin image first and select erase default configuration after flash.
After DD-WRT boots, flash the R6400-V1.0.0.26_1.0.14.chk file. Wait until Genie boots up.
Erase settings using reset button. Just push and hold the button -- Power LED will change color from white to orange, and after a few seconds will blink, then release button. Router should automatically reboot.
Thanks to https://rtr.ca/ for the files and the info.
**I can't find a stable 5ghz DD-WRT firmware yet**