I have an actiontec extender and I have to enable the 5g in the extender interface itself
Some extenders work differently than others. Netgears have a different way of setting up. After you place a Netgear in range of the router and run the setup the extenders are ready to go on both 2.4 & 5 Ghz and can be plugged into any power outlet inside or outside. Like I said the antenna on them are directional as to grab signal. They also have a arrow with green for good and yellow for weak distance. Quite easy and reliable.