with that antenna, ang assumption ko around 6 to 9 dBi ang antenna gain mo.
5W is 37dBm, AFAIK, acceptable receiver level is around -70dBm. EIRP is around 37dBm + 9dB or 46dBm. Free Space Loss at 2.4GHz is at 100dB per 1km, around 115dB at 6km. 46dBm - 115dB = -69dBm, so ideally, dapat sakop niya within 6km. kung may mga pader bababa pa 'yan, tapos meron ding range na malaki na ang lag ng WiFi.