Any impact on wifi environment when dropping DCA channels on 8540 WLC?

[ZoreoN81]

Hi, we are looking at switching off UNII-2 channels on our 5ghz radio on a 8540 wlc as they appear to cause a coverage issues for some devices that specifically don't play well when these channels are set to broadcast.

Wondering what impact would be to clients on 5ghz if we apply this change? Does the WLC need to disable the 5Ghz to take affect? Trying to get a sense of impact to wireless coverage in a critical clinical environment.

Appreciate any experience that anyone could share?

Thanks!

[ammahend]

Every time an AP changes channel, all associated clients to that AP will disconnect briefly. So the clients on AP which are on UNII2 channels will experience disconnection, moreover you have to disable 802.11a and b radio before changing the config for DCA and then enable it. 

would certainly recommend doing this in maintenance window. 

[Arshad Safrulla]

I would also suggest a DCA restart after the changes.

[Rich R]

> Trying to get a sense of impact to wireless coverage

Well it won't change your coverage generally (that's power levels) but since you'll have fewer channels to choose from there'll be more chance of overlapping cells on the same channel so if auto Tx power control is enabled that might result in power reduction which could impact your coverage indirectly.  Check impact carefully after making the change or use a predictive survey to estimate the impact before doing it.
If the affected devices are low bandwidth, and you have 2.4GHz band enabled, then you might be better off providing a separate SSID for them using only 2.4.  Sure you only have 3 channels to work with there but coverage should be good and if they're the only devices using 2.4 then that might be the better option rather than degrading the 5GHz service for everyone else.  Of course you should be raising this with the vendor of the troublesome devices - maybe they already have a firmware update to fix it?