AC 3504: Devices only compatible with 2.4 Ghz cannot connect to AP

[Joao P Pereira]

Hello there,

I have a customer with an Cisco AC3504 + 30 Cisco APs. Everything went well for years untill yesterday. The problem is that devices only compatible with 2.4 Ghz cannot connect to AP. The 5Ghz is working Ok.

Any of you have ever experienced a similiar scenario?

It is the issue due to any WLC software update?

Thanks a lot!

[marce1000]

 - Have a checkup of the current  controller configuration with : https://cway.cisco.com/tools/WirelessAnalyzer/

 M.

[neskemiquel]

Many devices state they are only compatible with 2.4 GHz networks or may prevent you from connecting them if your mobile is currently connected on 5 GHz.
Clover.com

[Arshad Safrulla]

Hi @Joao P Pereira , Did you check the AP slot 0, 2.4 radio is on admin up state? Did someone shutdown the radios by any chance? 

Did you perform any configuration changes recently on RF configuration on the WLC globally or profile wise which is attached to the AP's?

Software upgrades can cause issues, but I have never heard causing a similar issue which you are reporting. 

Use the show commands and if cannot decode the output yourself share it here, so we can help.

show advanced 802.11b summary

show advanced 802.11b profile global 

show ap config 802.11b summary