In normal mode, airMAX sends a confirmation frame (ACK) after receiving the data frame, but at longer distances, it is better to disable this mechanism by setting the Long Range PtP Link Mode checkbox in the settings.
Depending on the channel width, the distance at which you want to turn on the Long Range PtP Link Mode can be different.
40MHz: 16.5 miles (26.5 km)
20MHz: 35.6 miles (57.3 km)
10MHz: 72.3 miles (116 km)
5MHz: 144.7 miles (232.9 km)
Note: this information does not apply to airOS 7, there is another timeout ACK algorithm.