EM7421 failed in NETDEV WATCHDOG: wwan0 (cdc_mbim): transmit queue 0 timed out

[jyijyi]

Then this could be your hardware issue as i don’t see such problem with EM9291 in Ubuntu 18 PC.
I can establish data connection with mbim-network command:

Packet statistics of EM9293 and EM7431

how about using qmicli? owner@ubuntu:~$ sudo mbim-network /dev/cdc-wdm0 start Loading profile at /etc/mbim-network.conf... APN: hkcsl APN auth protocol: unset APN user: unset APN password: unset mbim-proxy: yes Querying subscriber ready status 'mbimcli -d /dev/cdc-wdm0 --query-subscriber-ready-status --no-close --device-open-proxy'... [/dev/cdc-wdm0] Subscriber ready status retrieved: Ready state: 'initialized' Subscriber ID: '454003067338878' SIM ICCID: '8985200012673388788…