Connect Nest WiFi with ATT Fiber Gateway

Hi there,

I recently switched to ATT Fiber from cable service.  I had the Nest WIFI router and points at my old house with cable working beautifully.  I now have the ATT Fiber Gateway and do not know how to use the Nest WiFi and points in my house.  I have awful service downstairs but upstairs it is great, of course, because that is where the gateway is.  Can anyone point me to what I need to do in order to use these points I have, right now they are just bricks serving no purpose and I'd like to get better service to the rest of the house.  I work from home so I don't want to screw up what is working but I also need downstairs to have better service.

Thanks so much,

Jo