iOS Devices Preferred Band on wireless?

Hi,

We have a pretty big wireless installation at my company. Recently we upgraded to a new wireless controller together with the new Cisco 3802i APs. Also we have done a lot of tweaking for Mac users both computers and cells.

I've been reading in an article that iOS 11 should prefer 5GHz over 2.4GHz, but the test I have been doing only let my Iphone 7 go back on 2.4 GHz every time I connect.

The setup we have now is that we have one corporate network and one guest network. The SSID is both on 2.4 GHz and 5 GHz. For our main laptops which are windows 10 machines we don't encounter this problem with 5 to 2.4 GHz it always choose the preferred band 5 GHz.

Is this a bug or is there anything I could do to force those devices onto 5 GHz?

Regards,

Robin