We’ve had three different teachs to our house and they’ve all tried different things. Cleaned filters assured hose is correct Nothing is fixing it for this model with an LF code would you not be able to repair the water inlet valve do you automatically go to thinking that it’s the control board

I am sure the techs tested the water inlet valve and found that the valve was good which is why they were saying it's the control board. If the valve is good and the LF error persists and there is proper water pressure being supplied to the washer then the only thing it can be is the wiring between the board and the valve or the board.