The LINX UART implementation uses /dev/ttyAMA0. This works on RPi2 but for RPi3 and 4 they repurposed that port and the UART pins map to /dev/ttyS0.
The RPi folks already saw this as an issue so now there is a symlink that always points to the correct serial device (/dev/serial0). Change the LINX implementation to use the symlink.
The LINX UART implementation uses /dev/ttyAMA0. This works on RPi2 but for RPi3 and 4 they repurposed that port and the UART pins map to /dev/ttyS0.
The RPi folks already saw this as an issue so now there is a symlink that always points to the correct serial device (/dev/serial0). Change the LINX implementation to use the symlink.