How to Enable sim card (WWAN) on Openwrt ZBT-WE826

I flashed my ZBT-WE826 but the sim card is not reading. I have tried to setup a WWAN interface but it still does not work.

Thanks for the help in advance.

consider using this OpenWrt-based firmware

Trying this might complicate issues for me since I do not have any experience with this firmware. I have a custom package I built for openwrt so I am not very confident trying out a different firmware.