Look in the link. That is from this same forum and they discuss this exact issue. Specifically @tsjk notes that downgrading the firmware makes the RNDIS vanish.
It seems I just have to successfully be able to flash it which I have been unable to do so far. The firmware versions are just the same as mine which are discussed in that thread.
I only tried on windows vms so far so I may try on my mother's windows machine instead.