So we managed to get this problem solved with the help of @aleksander0m!
The problem it turns out was simply that the profile that modemmanager was trying to connect to was incorrect and needed to be cleared.
Running qmicli -d /dev/cdc-wdm0 -p --wds-get-profile-list=3gpp
Returned:
Profile list retrieved:
[1] 3gpp -
APN: 'fast.t-mobile.com'
PDP type: 'ipv4-or-ipv6'
PDP context number: '1'
Username: ''
Password: ''
Auth: 'none'
No roaming: 'no'
APN disabled: 'no'
Somehow ModemManager ignored the APN defined in our system-connections file and chose fast.t-mobile.com
which worked for other SIMs but not the IoTDataWorks SIM which is expecting an APN of m2mglobal.
The solution?
Running qmicli -d /dev/cdc-wdm0 -p --wds-modify-profile="3gpp,1,apn=,pdp-type=ipv4v6"
Cleared that profile and now returns:
[1] 3gpp -
APN: ''
PDP type: 'ipv4-or-ipv6'
PDP context number: '1'
Username: ''
Password: ''
Auth: 'none'
No roaming: 'no'
APN disabled: 'no'
With an empty APN which solved the issue.
Now, WHY did mmcli or qmicli chose that t-mobile APN even though I never defined it (at least I think I didnt)? I’m not sure, but for diagnosing connectivity problems, checking these profiles via qmicli
will be a useful tool.