I recently upgraded to xFi from using my own modem and now experience a range of issues.

Initial Configuration:

xFi Gateway set to bridge mode, wifi broadcast turned off

Deco M9Plus physically plugged into gateway. Operating in router mode.

Con: The issue is that connecting the other 2 Decos have become my worst nightmare. I have removed, rebooted, and reset all of the devices multiple times. When I do get the correct order to getting all of the decos connected, it seems the others randomly lose connection. If one of the devices reboot, it's back to the drawing board. To top if off, my daughters iPhones won't connect and get the every so detailed "cannot connect" error. It's becoming a full time job of reseting, removing, adding each device. Frustrating!

What I've tried:

1. I tried calling xfinity. They just said they would ship me a new gateway and didn't offer any explaination. I asked for root cause, they said they could ship me a new device. It's on it's way and will be here in 3 days.

While I wait for the UPS shipment, I have also tried:

1. Changing the gateway back to router mode. Leaving deco in router mode.

Pro: We can connect to the main deco.

Con: I cannot connect any of the other mesh devices. They just blink blue and the app says it cannot find them.

2. Changing the gateway to router. Setting deco to Access Point. 

Pro: Nothing

Con: We cannot connect to the deco at all.

2. Changing the gateway to router. Changing deo to Access Point. Setting the DMZ on the gateway for the router IP.

Pro: Nothing

Con: We cannot connect to the deco at all. Also the gateway doesn't allow me to assign a static IP so it's kinda pointless.

At this point we have both devices setup as routers and it's my understing that can cause NAT issues. I don't feel this is an ideal setup. Plus, I can only have one deco connected at a time. I really like and need the decos to extend the internet throughout my house. I'm not a fan of the xFi gateway but it gives me unliminted internet. It would seem that these 2 devices should work in cooperation with each other. We can't all work in our living room, which is why I purchased the mesh devices. Any advice is MUCH appreciated!!