Are there any LTE PCIe modules (The small key ones that fit in a FW4B protectli unit) that work as a red failover in ipfire?
Did you consult the HCL?
There are a few on it, but generally anything that emulates a serial modem works.
I tried and failed however having a more determined look I’ve spotted the Huawei ME909u-521 in that list
That’s a good one