After i briked with DFU i dicided to reflash fresh. So i downloaded the latest firmware and with the help of stlink_v3 i flashed firmware with file RAK4270_v188.8.131.52_Boot+App_20211217.hex.
After that DFU 1.4 just give me timeout…
But with serial port tool i can talk with AT comands no problem.
Is the latest version of bootloader broken?