Troubleshooting Tip: Radio 3 from FortiAP K series not working (WiFi 6 and 7 not working)

[laltuzar]

Description	This article describes the limitations of FortiAP K series PoE modes and what works.
Scope	FortiAP G and K series. See datasheet for details on which models need 802.3bt or dual 802.3at to work in its Full mode.
Solution	Series G and K FortiAPs can be energized through the PoE and DC adapters. When connected through a DC adapter or PoE 802.3bt (60W to 90W), the FortiAPs will work on its 'Full mode': 802.3bt / DC : Full – Tx Power Full ; Chain 4x4; USB Enabled Whereas while connected through PoE 802.3at, the FortiAPs K series will work with Radio 1 (2.4Ghz) and Radio 2 (5GHz) at 17dBm maximum and USB will be disabled. Essentially, they will be working on 'Low mode': 802.3at : R1(2.4Ghz) and R2(5 GHz) operation in Low Tx Power 17dBm ; Chain 4x4; USB – Disabled This information can be confirmed in the FortiAP datasheet It is possible to verify which mode a FortiAP is working in by executing the command below on the FortiAP CLI: cw_diag power For example: ================================================================================ OUTPUT of command cw_diag power: ================================================================================ Power Detection Data: dc=0 ps1=1 af1=0 at1=1 psv1=0 bt1=0 ps2=0 af2=0 at2=0 psv2=0 bt2=0                       Budget lldp 22,0 poe 25,0 (dc=99 af=13 at=25 psv=60 bt=50 full=43.0 low=24.9) Current   Power Mode: low (4)  Oper Power Mode: low (4)     Radio 1: MaxTxpower 37 TxChainMask 0x01 RxChainMask 0x01     Radio 2: MaxTxpower 37 TxChainMask 0x01 RxChainMask 0x01     Radio 3: MaxTxpower 17 TxChainMask 0x01 RxChainMask 0x01     Radio 4: MaxTxpower 17 TxChainMask 0x05 RxChainMask 0x05         USB: disabled full:usb,all radios,txpower full,chain 4; high:2G/5G radio,txpower 17dBm,chain 2; low:disable all radios In this example, it can be observed that the FortiAP is working with a PoE 802.3at, which means that the FortiAP will work with Radio 1 (2.4Ghz) and Radio 2 (5GHz) at 17dBm maximum, Radio 3 (6GHz) will be disabled and USB will be disabled. How the AP is going to behave when being energized by 802.3bt single 802.3at or single 802.3af is described on the datasheet as the following example: