Using Cellular S7 Edge with German SIM Card

Hi there guys,

i am not new to this Forum but this time it's the first time i really have to ask a question.
I've got a Samsung Galaxy S7 Edge (Modell: SM-G935R4) from a Friend in the USA. I live in Germany.
When starting the Phone with my German SIM Card it's telling me the SIM is unsupported, of course 'cause it's a Cellular Device.

My Question:
Is it possible to get the SM-G935F (DBT) Firmware on it or flash any Custom ROM to get my SIM and perhaps the german language work?

What i've tried: (newest Odin, adb driver and Samsung driver + kies installed, everything works correctly and is displayed correctly)
- Installing newest DBT Firmware using latest Odin and also Odin Prince Comsy Edition -> giving me a fail
- flashing newest DBT Firmware with SM-G935R4 CSC using Odin -> fail
- root Phone using Verizon Guide -> works
- flashing twrp using Odin, also using flashfire apk on root -> fail
- flashing Custom Rom using flashfire apk on root -> fail
- flashing original Firmware for SM-G935R4 using Odin -> success (but well not useful)

Any useful Suggestions to solve my problem is really appreciated.

regards
titostoerfall

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