Configure Serial Port for Raspberry Pi
The Raspberry Pi (RPI) has the serial port (pins 8-Tx & 10-Rx) configured for a login shell by default, therefore you have to configure it for serial use in order for the Wireless Gateway to communicate with the RPI.
Open up a terminal window and type:
Select "Interface options"
Then select "P6 Serial" option.
Say "No" to the question "Would you like a login shell to be accessible over serial"?
The reply "Yes" to the question "Would you like the serial port hardware enabled?"
Exit Save and Reboot.
Special instructions for Raspberry Pi 3 and 4:
You need to disable Bluetooth so that the serial port will work.
sudo nano /boot/config.txt
Page down to the bottom of the file and add the following line:
Add the following line:
Exit, save and reboot.