Lots of threads here and on YouTube about lots of things interfering with the Wi-Fi only Mini.
I always fly mine in airplane and with little bother , I can regularly get 2k easily out here in the sticks.
I have more problems in the built up village area, and last weekend at the Humber Bridge meet was warning heaven, however there were 9 drones in the air at the time and we were all stood within 10m of each other.
Give airplane mode a go see how you get on?