ASUS PCE-AC68 not connecting to WiFi

[amarshonarbangla]

Bought a RT-AC68U router with PCE-AC68 card a couple days ago. It worked fine the first day. When I woke up the next morning, I saw it got disconnected. It wouldn't connect no matter what I do. I can see the available WiFi networks, but it refuses to connect. I reinstalled the latest drivers several times, reset my router, installed the card in a different slot, nothing is working. What I should do? Should I return it for a new one?