You won't see the 2.4ghz channels with a FCC Mini only the 5.8ghz ones, the FCC model does not have the circuitry for 2.4ghz
If you look at the Mavic Mini specs, the FCC model already has the highest transmission power compared to the 2.4ghz mode on the CE model.
The range is related to the transmission power so with the MM design, the FCC model already has the better range.
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Try some Yagi Antenna extenders (the 5.8ghz model has 6 poles) too see if they help with the range
Buy GoolRC Remote Controller Signal Booster Antenna Range Extender Amplifier Compatible with DJI
Mavic Air 2/
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