AP-228 with 2m cables or less, should be able to support 3-4mi in PtP with clean RF environment using the ANT-4x4-5314 antennas. Longer antenna cables will result in more loss, and lower distance. If you want numbers, the Outdoor VRD has some graphs to show Rate v Range. If your environment has high noise, if your cables are poor, if your alignment is bad, etc, then all bets are off.