Can I do a hard connection from my at&t router to the AC3000 Tri-Ban WiFi Range Extender?

I have AT&T fiber and I have the router upstairs in my house in a media closet I'm losing considerable amount of bandwidth with my devices down stairs. Orginally I bought the extenders that you just plu into the outlet, but they can never seem to keep a decent connection with my router up stairs.  Which leads me to the purchase of the AC3000 Tri-Band WiFi Range Extender. I'd like my devices down stairs to be able to feed off this extender.  And instead of connecting to the router wirelessly, I wanted to know could I run a hard wire connection to this extender for it to act as a bridge and still do it's job?