Better OpenWRT support

[jfrog]

@philipp

Network registration failed

Once again, forget about OpenWrt, QMI, MBIM, etc. for a while. Use a dumb terminal to troubleshoot your registration issue.

Follow the old topic:

Troubleshooting connectivity on T-Mobile USA and RM520N-GL

Forget about OpenWRT, ModemManager, MBIM, QMI, etc. for a while, dumb terminal is your only friend at this stage. As said above, you need to work with “AT commands via ttyUSB”.