WiFi connecting as 802.11n and not 802.11ac

My 5GHz range on my HG633 is set up to 802.11a/n/ac. On my windows 10 laptop, if I look at my wireless connection properties, the speed is 130Mbps, but the protocol its using is 802.11n.

Is there a reason why I'm not connecting using 802.11ac?

Thanks

Paul