Importance of the right cable
Sending G codes from a PC or laptop requires several key elements.
Properly configured cable. Anderson recommends ordering a Fanuc serial from https://www.machinetoolcables.com/
A Serial port via really old laptop or USB to serial emulator
Understanding that the baud rates from the PC to the Fanuc are configured to send and receive at the same rate. (4800 or 9600 bits per second)