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AP 3800 does not support dual band

Hello all,

I am trying to configure AP 3800 support 5GHz with below commands but not succeed(please see attached file also). Please help


(Cisco Controller) >config 802.11-abgn band ap VNSGNB09AP 5GHz

Radio [Slot 0] does not have external antenna plugged into a DART Connector Dual 5GHz Operation Not Allowed


Rasika Nayanajith
VIP Mentor

What are you trying to achieve? Use dual 5GHz radio working or just 5GHz enable on this AP?

Pls post "show version" of this AP to check. Is this AP managed by a central WLC or is it Mobility Express deployment?



I have four 3800 and four 3700 with 3800 is virtual controller (Mobility Express)

3700 is supporting both 2,4GHz and 5Ghz.

But 3800 support only 2,4GHz and I want 3800 support both.


cisco AIR-AP3802E-S-K9 ARMv7 Processor rev 1 (v7l) with 1028616/349984K bytes of memory.
Processor board ID FGL2316A89T
AP Running Image :
Primary Boot Image :
Backup Boot Image :
1 Multigigabit Ethernet interfaces
1 Gigabit Ethernet interfaces
2 802.11 Radios
Radio Driver version :
Radio FW version :
NSS FW version : 2.4.26

Base ethernet MAC Address : 78:BC:1A:49:6D:0C
Part Number : 73-100821-03
PCA Assembly Number : 000-00000-00
PCA Revision Number :
PCB Serial Number : FOC23194562
Top Assembly Part Number : 068-100532-05
Top Assembly Serial Number : FGL2316A89T
Top Revision Number : C0
Product/Model Number : AIR-AP3802E-S-K9

on that controller (ME AP), pls get the following output to see what are the channels of those AP.

show advanced 802.11a summary





Hi Rasika,

Here you are


(Cisco Controller) >show advanced 802.11a summary

Member RRM Information
AP Name MAC Address Slot Admin Oper Channel TxPower
-------------------------------- ----------------- ---- -------- ----------- ------------------ -------------
VNSGNB04AP 00:62:ec:3e:8d:90 1 ENABLED UP (100,104,108,112)* *1/6 (17 dBm)
VNSGNB09AP 5c:5a:c7:13:ba:00 1 ENABLED DOWN 36* *1/6 (16 dBm)
VNSGNB07AP 70:df:2f:8a:61:00 1 ENABLED UP (64,60,52,56)* *1/6 (17 dBm)
VNSGNB03AP e0:0e:da:df:4f:80 1 ENABLED UP (40,36,44,48)* *1/6 (17 dBm)
VNSGNB05AP 00:62:ec:80:70:90 1 ENABLED UP (64,60,52,56)* *1/6 (17 dBm)
VNSGNB06AP 2c:33:11:3e:33:40 1 ENABLED UP (36,40,44,48)* *1/6 (17 dBm)

* global assignment

As per that, only a single AP having this issue of 5GHz down. Is that right?

VNSGNB09AP 5c:5a:c7:13:ba:00 1 ENABLED DOWN 36* *1/6 (16 dBm)

What is the difference between that AP vs others? Have you plugged external antenna ? is that same as with others?


As a side note, noted that you setup 80MHz channel width and AP use the same channels (VNSGNB07AP same as VNSGNB05AP, VNSGNB03AP same as VNSGNB06AP). If these AP in nearby, it will interfere with each other. Better use 40MHz channel width to prevent co-channel interference.




Hi Rasika,

Yes, that right. VNSGNB09AP is 3800 and the others is 3700. Only VNSGNB09AP is facing this issue.


There are no external antennas for 3800, I dont buy them yet. Is it necessary to have ex antennas for 5GHz support ? It would be disaster.


For your side note, I tried to setup only 3800 SSID, but no 5GHz support, so probably channel width does not cause problem.

Jurgens Lombard

Is this AP by any chance connected to a different model switch than the other AP's? If the AP is connected to a switch that is proving only PoE and not PoE+ the radio's on the AP won't come up.

See PoE requirements:

I am using the same switch for all APs. It is 2960X-24TS-L which does not support PoE. Maybe it cause the issue.


But my colleague in another site, use the same switch and the same AP 3800, there is no issue with supporting 5GHz.


Is there another reason ? version of ios or in configuration 

Open a TAC case and see what they say. Could be a bad radio or manufacturing issue. Has this worked before?
*** Please rate helpful posts ***

Nope, it has not worked before. But 3800s in another company site are working with 5GHz support. So I assume there is something wrong in configuration.

Does your colleague use the same power injectors as what you are using and can you confirm the model number the power injector you are using?

Yes the same Power injectors for all our 3800 APs. The model of power injector is "AIR-PWRINJ6 V01"


(Cisco Controller) >config 802.11-abgn band ap VNSGNB09AP 5GHz

Radio [Slot 0] does not have external antenna plugged into a DART Connector Dual 5GHz Operation Not Allowed

The 2800/3800 APs have two separate radios - a 5 GHz radio, and also a dual-band radio which can operate on either 2.4 GHz or 5 GHz (but not both at once).

In the text I quoted above, you are trying to configure the dual-band radio for 5 GHz, which means you are trying to disable 2.4 GHz and use both radios on 5 GHz.

In order to do dual 5 GHz operation, dual set of antennae are required. That is what the error message is telling you. One set of antennae cannot be shared by two radios on the same band. You can only share two radios on one set of antennae if the two radios are on different bands.

You say you want dual band, yet what you are configuring is dual 5 GHz. If you truly want dual band then you should configure the dual-band radio for 2.4 GHz and use the 5 GHz radio for 5 GHz.

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