Hey, I don't have IAP-315 to hand but I do have a IAP-225 and it does support 80MHz w, so i'm wondering if the same options are on the IAP-315 but for 160mhz.
Under the "RF" settings and then the "Radio" tab, have you enabled "Very high throughput" to enable 11ac? Then again under "RF", I have the option to enable 80MHz support, do you have the same options for 160MHz support?
Cheers,
Craig