To connect at 802.11ac performance you must have an 802.11ac adapter, for example the TEW-805UB.
https://www.TRENDnet.com/products/product-detail.asp?prod=100_TEW-805UB
Please also ensure the Router is secured using WPA2 AES encryption levels. By default the TEW-823DRU is preconfigured with WPA2 AES.