I’m using the microG lineageos builds, and I have problems with signal, especially when in roaming: phone takes very long time to register (compared to other phones of people coming with me), and very often switches to 2G - switch to airplane mode several times usually helps.
I noticed that for older FP models, there was a community-provided way to update the firmware in the modem (✏ FP2 modem firmware). Is there something like this for FP4? Or could I just fastboot flash one/some of the files that are contained in the original firmware zip files?