I am kinda stuck with this as well.
The LTE dongle in my case is a Brovi 3372-325 with the mentioned firmware from the entry post.
Attempt 1:
- connect as LTE interface
- failed, no such interface appears
- modem mode mbim or auto
- EDIT: See below, it actually came up as lte interface, but a technical problem makes the lte interface unusable
Attempt 2:
- serial/ppp
- connection buildup works with german Telekom (APN internet.telekom, user tm, password telekom)
- Tx counters go up
- no Rx counters go up
- NAT and Firewall are verified to be correctly set up
Attempt 3:
- direct connection on a Windows machine
- is detected as RNDIS device
- works out of the box
- webinterface at http://192.168.8.1/ works
- but as this is some HUAWEI produced third party brand stick, there is no bridge settings or such
Am I out of luck here?