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【FAQ】Why sometimes the AP can’t run normally when powered by PoE?

Dec 04, 2019

If the switch follows the IEEE-802.3af (PoE) standard, it supplies insufficient power to drive the AP. The Wi-Fi access point needs IEEE-802.3at (PoE+) to power on. Therefore, if the switch with the capability of power over Ethernet is not the PoE+ device, the AP could not work normally. The table compares the capability of these two standards.

802.3af   (PoE)

802.3at   (PoE Plus)


44~57V DC

50~57V DC



CAT-5   or better

Load Device Power






In addition, the quality of cable from PoE switch to AP is important, the unqualified cable could not supply enough power to AP due to the voltage rapidly decline if the length exceeding 80 meters. When AP is not supplied by sufficient power, it usually appears as following:

. AP can’t boot up 

. AP sometimes can and sometimes can’t boot up 

. AP can boot up, but it will reboot during transmission 

. AP can boot up and transmission OK, but the wireless network is too unstable to keep association with user endpoint

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