Thanks for all the responses to this thread. I returned the second ST Hub as your responses and my further research led me to conclude that what i was attempting was not going to work. (Which i’m still somewhat amazed by).
House is 5000 sqft, made of steel, cement, and glass. It’s a blackhole for wifi, a faraday cage so to speak.
ST hub is centrally located in stairwell connecting two floors.
I ordered a TP-Link AC1200 Wi-Fi Range Extender w/ Gigabit Ethernet Port to see if i can futz with the hub’s position to get better coverage. The suggestions to add additional z-wave plus devices is another possible solution. Currently, the network z-wave mesh is probably too sparse with about 4 devices per floor. (All z-wave, not z-wave plus which i understand now has a much greater range).
Question: Is there any type of IOS app that can test linkage strength between z-wave enabled devices? It would be great to be able to see where the weak links are somehow. Seems like there must be something like this. The ST app can “repair the z-wave network” but it doesn’t really give you any details about the health of said network.
Thanks again for all the responses and suggestions.