Recently moved and finally on AT&T fiber and I want to hook up my Deco BE85 system to run instead of the ATT gateway.  
 

Going through using my own router is usually an easy setup and I feel I'm doing something that's so simple but I cannot get my deco paired with my fiber. I've tried the IP pass through and once I try to go to the deco app, it never can't connect to my network. 
 

When it comes to wiring, do I keep the fiber line connected to the gateway and then just run an Ethernet to the deco unit? 
 

Any help would be much appreciated because I need to figure this out!