apple tv won't connect to wifi without ethernet

I purchased a second-hand restored Apple TV (Gen 3) from a reputable seller and I'm having trouble connecting to the internet. I made sure it isn't my WiFi that's the issue and I've tried every solution I could find online (resetting, changing time zone, etc). Finally I discovered the only solution was to connect my Apple TV to my router using an ethernet cable, but this is only a temporary solution since the router is in the kitchen and I need the TV in a different room. When I unplug the cable the internet goes away again. It's very frustrating. Any solutions?