Huawei modem in NCM mode

[eblot]

Hi,

Is there any guide to set up an LTE fallback gateway using a cheap Huawei USB modem key (12d1:1f01 Huawei Technologies Co., Ltd. E353/E3131)?

I've successfully switched it to NCM mode (12d1:155e) or ECM mode (12d1:14db), but I do not know what to do to move forward:

* in NCM mode, ue0 interface is successfully detected:
   
   ue0: flags=8802<BROADCAST,SIMPLEX,MULTICAST> metric 0 mtu 1500
   ether 00:1e:10:1f:00:00
   nd6 options=23<PERFORMNUD,ACCEPT_RTADV,AUTO_LINKLOCAL>
   
   however I do not know how to configure such an interface with opnsense;

 * in ECM mode, the network interface does not show up in opnsense UI (nor via CLI/SSH).

In this later mode, Linux automatically assigned a local IP to the interface from the integrated DHCP server on the USB modem key (192.168.8.0/24), but I did not find how to do something akin to Linux with opnsense/freebsd.

Thanks.