@davidwess I've exactly the same problem and have been told by TP-LINK that there is no solution. I have a outdoor TP-LINK Access Point AC1200 and been told OMADA MESH is incompatible with DECO MESH. In my opinion MESH incopatibility between two TP-LINK lines should be out there in magazines and reviews so customers are not misleaded. 

davidwess wrote

I have an S4 mesh network in my home, with five Deco's. Everything works fine, no issues. I would like to get better coverage outdoors in my back yard. Is there anything in terms of an outdoor unit that will seamlessly integrate with my current Deco setup and provide outdoor WiFi?

@Pinheim Thanks for the response. I am disappointed and surprised, because there must be plenty of folks that need meaningful and consistent access in their yards. This should be fixed.