Will a SDR-capable radio switch back to 2,4 GHz when conditions change?

[AnonymousM]

After we had enabled SDR on AP250 and AP550 we found several areas where neighboring APs all switched the wifi0 radio to 5 GHz. The 2,4 GHz signal is very weak in those areas so that we assume that it would be better to switch back some of those radios to 2,4 GHz. Should this happen automatically when the according APs recognize that the conditions have changed? Or do we have to force these APs to use the 2,4 GHz band manually? 

(This question was transferred from HiveNation: https://community.aerohive.com/aerohive/topics/will-a-sdr-capable-radio-switch-back-to-2-4-ghz-when-conditions-change)

[AnonymousM]

Hello Sam,

thank you for your answer.

Since we are a college in Germany the most clients are students with their own devices. Although the most of them connect to the 5GHz band there are roundabout 20 to 25 percent who have only 2.4GHz capable devices. Therefore we still must provide 2.4GHz on the whole Campus.

Following the SDR guide you mentioned APs switch to 5GHz when they don't find a suitable channel in the 2.4GHz band. I assume "no suitable channel" means that the AP receives strong signals from other APs on all possible channels. However, in our case RF holes were the result: Areas with absolute weak signal in 2.4GHz.

Now we are still waiting for a switch back to 2.4GHz of one ore more of the APs in that areas. Our impression is that these APs need a little bit help (by disabling SDR and assigning a 2.4GHz profile manually). However, we like to avoid such configuration changes because this leads to confusion.

[samantha_lynn · Accepted solution]

According to the documentation on SDR, these scans automatically shut down 2.4 GHz radios when they are not required for good coverage. Since both of your AP models (250 and 550) are dual 5GHz capable, would it be feasible to use only 5GHz in your network? It is a stronger signal, so as long as you have enough APs to cover your area in 5GHz signal (it doesn't go as far as 2.4), then it might be better to use dual 5GHz.

The documentation I was referring to is here- https://docs.aerohive.com/330000/docs/help/english/ng/Content/gui/configuration/configuring-sdr-settings.htm?Highlight=SDR

We also have a set up guide for SDR that has some tips: https://thehivecommunity.aerohive.com/s/article/SDR-Profiles

Hope this helps.