raspbian - Error while connecting to data using Modem Manager in Raspberry Pi

Question

I am using Raspberry Pi Compute Module 3 with Raspbian Buster OS. I have connected Quectel EC25 modem and trying to connect to internet using Network Manager and Modem Manager tool.

Whenever I use new Airtel or Vodafone SIM cards, either Couldn't connect bearer: 'QMI protocol error (14): 'CallFailed'' or couldn't start network: QMI protocol error (79): 'PolicyMismatch' error occurs. After random hours (max. 50 hours), this error gets resolve and connection is being established successfully. I am not able to figure out what exactly the issue is.

List of error as per logs:

Jan  4 15:43:52 24Seven-78 ModemManager[6574]: [/dev/cdc-wdm0] Registered 'wds' (version 1.67) client with ID '22'
Jan  4 15:43:52 24Seven-78 ModemManager[6574]: <info>  error: couldn't start network: QMI protocol error (79): 'PolicyMismatch'
Jan  4 15:43:52 24Seven-78 ModemManager[6574]: [/dev/cdc-wdm0] Allocating new client ID...
Jan  4 15:43:52 24Seven-78 ModemManager[6574]: [/dev/cdc-wdm0] Registered 'wds' (version 1.67) client with ID '23'
Jan  4 15:43:52 24Seven-78 ModemManager[6574]: <info>  error: couldn't start network: QMI protocol error (14): 'CallFailed'
Jan  4 15:43:52 24Seven-78 ModemManager[6574]: <info>  call end reason (1): 'generic-unspecified'
Jan  4 15:43:52 24Seven-78 ModemManager[6574]: <info>  verbose call end reason (2,237): [internal] (null)

Jan  4 16:46:54 24Seven-78 ModemManager[6574]: <info>  Modem /org/freedesktop/ModemManager1/Modem/1: state changed (registered -> connecting)
Jan  4 16:46:54 24Seven-78 NetworkManager[535]: <info>  [1609759014.9170] modem["cdc-wdm0"]: modem state changed, 'registered' --> 'connecting' (reason: user-requested)
Jan  4 16:46:55 24Seven-78 ModemManager[6574]: <info>  error: couldn't start network: QMI protocol error (14): 'CallFailed'
Jan  4 16:46:55 24Seven-78 ModemManager[6574]: <info>  call end reason (1): 'generic-unspecified'
Jan  4 16:46:55 24Seven-78 ModemManager[6574]: <info>  verbose call end reason (6,55): [3gpp] multiple-connection-to-same-pdn-not-allowed
Jan  4 16:46:55 24Seven-78 ModemManager[6574]: [/dev/cdc-wdm0] Allocating new client ID...

QMI Protocol Error 2,237 means ip-support-mismatch and 6,55 means multiple-connection-to-same-pdn-not-allowed. I am not able to understand these and how to resolve them.

Following is the Network Manager connection details:

[connection]
id=MobileConnection
uuid=67bfdda8-e92d-4407-880d-eaf3294a5180
type=gsm
autoconnect-priority=3
interface-name=cdc-wdm0
permissions=

[gsm]
apn=www
number=*99#

[ipv4]
dns-search=
method=auto
route-metric=50

[ipv6]
addr-gen-mode=stable-privacy
dns-search=
method=auto

I am attaching debug logs of Modem Manager.

Logs

Answer 1

等待大神答复