Add an older Orbi 860 system to new Orbi 970 system?

Hi.  Hoping someone can help clarify.  I have an older 860 system with a couple of add on satellites for broader coverage.  Has always worked fine.  I bought a new 970 system which is great and super fast.  I want to add the older system because it's still in good shape, and to extend coverage to many smart devices, plugs, camercas light etc.  I put the older 860 in access point mode, and attached it by ethernet from it's internet port  to the 970's10g port.  Each setup has it's own SSID, mainly so I don't have to reset 100 devices.  It seems to be working, but the statues are wrong in the orbilogin.com and the app.  The new system seems to be correct, but the older system shows config, or disconnected, etc.  Tech support has said this would work and I'm following their instructions, but it's still not showing up correctly.  The firmware is updated for both systems, and I've reset the router on the older system and reconnected.  Any ideas what is causing this, and if it can be fixed and how to correct it?  Thank you