TPLink Archer C20i no internet on 5Ghz when using AC

I'm going to guess this is just due to the hardware but with openWRT if the 5Ghz interface is set to AC I notice devices report no internet. If you set it to N then the devices get internet.

On the stock firmware the AC setting is usable.

Anyone know anything about this router?

Not very likely, you need to provide additional information.