I used to force FCC on my old Phantom 3 Standard via telnet and ftp or via a nice windows script created by a phantompilots user. Not the same case for the Mavic. Has not been done by anyone as long as I know..
I am in Europe and at rural areas I have no problem with range. I have flown to distances 4-5 km away. Either you fly on a heavy wifi polluted area, or you dont orientate your controller antennas correctly.
Also, bare in mind that connection between the quad and the controller must be unobstructed.