With network.PPP device hangs after several hours of operation

Port, board and/or hardware

rp2

MicroPython version

MicroPython v1.25.0-preview.72.g2e796d6c3.dirty on 2024-11-30; Raspberry Pi Pico W with RP2040

Reproduction

import time
import network
from machine import UART, Pin

import constants

class Modem:

def __init__(self, log):
    self.log = log

    self.uart = UART(0, 115200, rxbuf=1000)

    self.power_pin = Pin(constants.MODEM_POWER_PIN, Pin.OUT)
    self.status_pin = Pin(constants.MODEM_STATUS_PIN, Pin.IN)

    self.ppp = None

def send_at_comm(self, command, timeout=5):
    self.log.info("AT:", command)

    compose = f"{command}\r\n".encode()

    try:
        self.uart.write(compose)
    except:
        self.log.info("Error occured while AT command writing to modem")

    time.sleep(0.1)
    return self.get_response(timeout)

def get_response(self, timeout=5):
    response = ""

    timer = time.time()
    while True:
        time.sleep(0.1)

        if time.time() - timer < timeout:
            while self.uart.any():
                try:
                    response += self.uart.read(self.uart.any()).decode("utf-8")
                except:
                    pass

            return response
        else:
            return "timeout"

def connect_PPP(self):
    self.reset()

    time.sleep(2)
    result = self.send_at_comm("ATZ")
    self.log.info(result)

    time.sleep(2)
    result = self.send_at_comm("AT")
    self.log.info(result)

    time.sleep(2)
    result = self.send_at_comm('AT+CGDCONT=1,"IP","super"')
    self.log.info(result)

    time.sleep(2)
    operator = self.operator()
    self.log.info(result)

    time.sleep(2)
    result = self.send_at_comm("ATDT*99#")
    self.log.info(result)

    time.sleep(2)
    self.ppp = network.PPP(self.uart)

    time.sleep(2)
    self.ppp.connect()

    while not self.ppp.isconnected():
        self.log.info("connecting PPP")
        time.sleep(2)

    self.log.info("PPP connected", self.ppp.ifconfig())

    return operator

def operator(self):
    command = "AT+COPS?"
    response = self.send_at_comm(command)
    self.log.info(response)

    operator = None
    access_technology = None

    response = self.preprocess_response(response)
    pos = response.find("+COPS: ")
    if pos:
        splitted = response[pos:].split(",")
        self.log.info(splitted)
        operator = splitted[2]

        if splitted[3] == "0":
            access_technology = "GSM"
        elif splitted[3] == "8":
            access_technology = "LTE CAT M1"
        elif splitted[3] == "9":
            access_technology = "LTE CAT NB1"

    return {"operator": operator, "access_technology": access_technology}

def power_toggle(self):
    self.power_pin.high()
    time.sleep(2)
    self.power_pin.low()

def is_on(self):
    value = self.status_pin.value()
    if value == 0:
        return True

    return False

def reset(self):
    self.log.info("reseting modem")
    if self.is_on():
        self.power_toggle()
        time.sleep(2)

    self.power_toggle()

def preprocess_response(self, data):
    return data.replace("\r\n", ",")

Expected behaviour

PPP works until disconnect

Observed behaviour

Device hangs after several hours of operation. Im using Sixfab PicoLTE (Pico W integrated with Quectel BG95-M3 modem).

Additional Information

No, I've provided everything above.

Code of Conduct

Yes, I agree

Start by reproducing the supplied network.PPP example on the RP2040 Pico W with the Sixfab PicoLTE and BG95-M3 modem, monitoring the UART and connection state until the hang occurs. No repository file or test is named; done would be identifying the failure in PPP operation and documenting a reproducible cause and regression coverage.