Reply To: My Python bridge breaks every time the Arduino comes back as a different COM port

I’m a beginner too but I had exactly this with my weather station PC last winter, and the fix was to stop caring about the number. Find the port by what’s plugged into it instead. pyserial can list ports with their USB ids and serial number:

from serial.tools import list_ports

def find_arduino():
    for p in list_ports.comports():
        print(p.device, p.vid, p.pid, p.serial_number, p.description)
        if p.vid == 0x2341 and p.serial_number == "85736323838351F0B0E1":
            return p.device
    return None

port = find_arduino()
ser = serial.Serial(port, 9600, timeout=2)

Run it once to print yours and copy the serial number in. 0x2341 is the vendor id of genuine Arduino boards. If yours is a clone with a CH340 chip (vid 0x1A86), careful: those usually have no serial number, so with two clones you can’t tell them apart and you’d match on p.location (the USB socket) instead.

Also wrap the read loop so it looks for the port again after an error instead of dying, then people can replug whenever they like.