Description

When connecting an AP to a switch with PoE, we may encounter situations where functionality is limited due to the power supplied; this article will describe a potential issue

Symptoms

  • AP working on reduced funcionality mode
  • Switch not providing the proper POE power level

Solution

When checking the AP requirements we noticed that POE on BT mode is required for full funcionality


On 802.3at power, the AP will operate with reduced functionality. If all three Wi-Fi radios are enabled, they will operate at 2x2:2. If only two Wi-Fi radios are enabled, they will operate at 4x4:4 The scanning radio, BLE radios, GPS and UWB are always enabled regardless of power source.


For reference

https://www.juniper.net/documentation/us/en/software/mist/mist-wireless/topics/ref/ap-poe-requirements.html

 

When checking the current POE mode we noticed that the switch was running AT mode

mist@EX> show poe controller | no-more 
Controller  Maximum   Power         Guard    Management   Status        Lldp
index       power     consumption   band                                Priority 
   0        1700W     93.00W          0W     Class        AT_MODE       Disabled


As per the feature compatibility the switch used on this case(EX4300MP) supports BT POE mode, other switch models will required further validation


https://apps.juniper.net/feature-explorer/feature/3401?fn=Power%20over%20Ethernet%20IEEE%20802.3bt


We will need to upgrade the firmware to BT mode, this ideally after hours, using the folloing guide:


https://www.juniper.net/documentation/us/en/software/junos/poe/topics/topic-map/poe-bt-upgrading.html

Modification History

2026-03-19 : Article Created