RV55 Serial AT Commands

I’m attempting to dynamically modify the serial port (single mode) from reverse telnet/ssh to Normal AT at startup to run scripts via AT commands. The user manual states the following: “On
startup, typing ATMD0 within 5 seconds changes the mode to normal (AT command)
mode”, but I seem to be unable make this work. I can set the mode to normal AT from the GUI and then switch to reverse telnet via AT command ATMD08 but this may not necessarily be the same thing. Any help would be appreciated.