Repair Imei for Samsung S7 G930F

Hi I have a Samsung S7 G930F in black list and i want repair IMEI for unlock it
The firmware on it is G930FXXS2ERH6 Android 8.0.0 how can i repair Imei?

I have repaired some G930F in past but they had Android 6.0.1, I must downgrade it? What is the Firmware that can i use?

Thanks