I bought a RAK7258 in-door gateway and several RAK811 breakboards last month.
I tried flashing the RAK811 module with latest firmware found on RAK website: https://downloads.rakwireless.com/en/LoRa/RAK811/Firmware/
I followed the steps mentioned in user manual, flashed boot loader v3.0.2 and upgraded the firmware successfully. However, when I reset the module and send AT command through serial port, I got nothing. Some screenshot are enclosed.
Any help is greatly appreciated.