Can't see 5ghz on a6210 with a 6400 1750 netgear router and other router/modem on desktop

Hi, just fyi, I tried the 6200 adapter that I have as well and it had the same issue, not showing 5ghz channel with my (netgear) router.  However, it is showing 5ghz with other routers in the area.  

I really feel angry as there is no way to get support from netgear without paying $50 (as I bought it years ago).  I feel I should be able to get support as it is an issue I would have had if I had bought it right now.  And none of the threads detailing this problem have had any response from netgear's official reps on this board that I can see :(.  It is like netgear has abandonned those of us with this issue.  

I have updated the router, checked its settings, done everything I can think of.  I am happy to try a different channel if someone can tell me which one.  Or I am happy to try a different setting either in windows or on the router if someone can tell me which one.  

I don't want to have to get a new adapter from another company but I will do so soon if this does not resolve.  Or I will run the adapter with windows generic drivers which I can only access when I reinstall windows and don't install netgear's drivers.  Yasmine