OSError: Network card not available for Wifi (pycom4)

[A Former User]

Hey,

For study i have setup an MQTT Broker & we have to connect to this broker with a pycom4.
Currently everytime i connect to my wifi in boot.py (This works fine).
Then when the MQTT Client tries to connect or a urequest is done, it throws the error: OSError: Network card not available.

Why is it saying this, when it has connected to wifi with no issue??
Setting up wifi...

Setting up wifi... (Wlan-piot)
Wifi has been setup! (192.168.32.25)
('192.168.32.25', '255.255.255.0', '192.168.32.134', '192.168.32.134')

Error:

RTC Set from NTP to UTC: (1970, 1, 1, 0, 0, 9, 602235, None)
Traceback (most recent call last):
  File "main.py", line 32, in <module>
  File "/flash/lib/mqtt.py", line 56, in connect
OSError: Network card not available

boot.py

from network import WLAN (Line 3)
import machine
import ENV

#Wifi setup
print("Setting up wifi... (" + ENV.SSID + ")")
wlan = WLAN(mode=WLAN.STA)
if ENV.STATIC_IP:
    wlan.ifconfig(config=ENV.CONFIG)

wlan.connect(ssid=ENV.SSID, auth=(WLAN.WPA2, ENV.PASS))
while not wlan.isconnected():
    machine.idle()
print("Wifi has been setup! (" + wlan.ifconfig()[0] + ")") 
print(wlan.ifconfig())

main.py

import pycom (Line 3)

from mqtt import MQTTClient
from network import WLAN
from time import sleep
from timestamp import timestamp

import machine
import socket
import urequests

import ENV

def sub_cb(topic, msg):
    print("mqtt::",topic,"msg[",msg,"]")

#Device setup
pycom.heartbeat(False)
clock = timestamp()
sleep(2)

#res = urequests.post('http://' + ENV.MQTT_URL, json={"emotie": 0})
#res.close()
#print(res.status_code)
    

#MQTT Setup
client = MQTTClient(ENV.DEVICEID, ENV.MQTT_URL, port=1883)
client.set_callback(sub_cb)
client.connect()

#Our main program
while True:
    print("Sending")
    ##client.publish(topic="piot/storedata/"+ ENV.DEVICEID + "/ping/" + clock.getTimestamp(), msg="pong")
    sleep(1)

[A Former User]

Hey, yhea before when i put it in the main.py it took long to connect, and sometimes just wont.
Still seems to be the problem when setting up the connection in main.py, but atleast the client works after no problem...

EDIT: Because in the boot.py it connects realquick everytime.

[g0hww]

Hmm. This is just a quick guess, but it looks to me as if your wlan object goes out of scope when boot.py completes. I suspect that its destructor takes down the network.

I would try moving all the wifi setup code into main.py and run it before instantiating the MQTTClient object.

Also, consider that you may eventually need to handle wifi dropouts or MQTT client disconnects due to underlying TCP connection failures at some point depending on what you ultimately expect this to do and for how long.