Force 5ghz Channels

I'm having a problem with one iphone 6 which has a damaged wifi. 

I would like to try and force the phone to use only the 5ghz frequency if possible to test if just a particular antenna is bad in the phone.

So, since I don't see any clear ways to set my router to only use the 5ghz frequency, can someone guide me in setting it up? I only have iphones connecting to the wifi which all have 802.11ac capabilites, so I should be able to force it onto one frequency or another. As you can see from the clip below, it is running at 2.462 frequency. I've unchecked ' Enable 20/40 MHz Coexistence' already, and Channel 11 is clear in my area. Any thoughts and ideas are appreciated. 

Is this router even capable of running only 5ghz frequency, or do I need to buy a 802.11ac wifi router? 

This is just for testing, so I'd prefer not to have to purchase a new router if I can avoid it.

Below is a snippet of what a wifi channel scanner sees.