Hi iphone 5 won't either connect to 5 ghz

You must know i'm new with advanced settings on
these routers, but there is something i'm missing
with the 5 ghz setup? Maybe i should start all over
and follow install instructions from the dlink pdf file
setting up 2.4 and 5 ghz. AC standard is 5 ghz,right?
What about teamviewer? Is it possible for you to help
this way if we can find the time for it?