Q. What is the highest PoE range?

A better way to frame this would be to question the maximum distance over which data and power can be transferred using PoE. This depends on the voltage rating used. If it is a 24-volt passive system then the maximum distance or range over which the data and power can be transferred is approximately 100 to 150 feet. Similarly if the voltage is 48 volts then the maximum range is about 300 feet.