I don't have a Mini myself, but instead a
Mavic Air 1 which have the same transmission system (Enhanced WiFi).
You mainly have 4 thing's to consider when it comes to all DJI transmission systems (including DJI Enhanced WiFi & DJI Occusync) & range.
1. How you point the RC controller antennas. The flat side should always be pointing at the drone, not the tips. So if flying at a distance have them folded vertically, & if flying right above yourself, have them folded horizontally.
2. Choice of transmission frequency & penetration and risk for interference. If you have the possibility to chose between 2,4GHz & 5,8GHz you should know that 2,4 penetrate better & by that theoretically giving more range, but is very sensitive to interference from other WiFi signals. 5,8 penetrate slightly worse & by that gives a shorter range, but is less affected to interference as 5,8 isn't used as much as 2,4.
3. Totally free Line of transmission sight between the controller & drone is required. WiFi doesn't penetrate mountains, hills, houses & trees/forrests, the water in fully leaved trees mainly completely block WiFi signals.
Here a visual pic to show how obstacles, height & range are connected.
View attachment 165388
4. Signal extenders... if just speaking of the cheapest ones that just snaps onto the RC antennas (Yagi-Uda extenders), they make a difference by creating a more directional signal from the controller making you gaining some more range but in return the direction you point the controller will become even more important.
Here how Yagi-Uda looks on a DJI controller similar to what you have for your Mini. The one with long pins is for 2,4GHz & the one with shorter is for 5,8GHz (you don't have one of each on, instead decide which frequency you want to use on the controller & then put on the ones intended for that frequency on both antennas.)
View attachment 165389
I have reached out slightly over 4km with my
Mavic Air 1 with Yagi-Uda, on 2,4GHz over a deserted farm land on 100m height... could have flown longer but had to turn depending on the remaining battery.
*EDIT* forgot to mention that the flown distance above with my
Mavic Air 1 was done in FCC mode.