Mount MTD UBIFS on Asus AC86U router

Hello
I found this thread: https://forum.openwrt.org/t/solved-how-to-mount-ubifs-in-openwrt-kirkwood/32443

but it does not work on ASUS.
I am trying to mount an MTD image to read its content, but nothing works.
I've copied the MTD with DD command.
Does anyone know how to read/write to MTD UBIFS image?