@goodwillhinton,

I would definitely recommend reading through the pinned post from another user that goes into extreme detail about how these devices are wired and could work in different situations. In most cases, users have had success configuring these devices like this. However, there are a lot of things to consider. The pinned post can be found here:

HS210 3-Way Installation Tutorial

If you are having issues configuring the device without the extra unit, I recommend adding the extra unit to the setup. It is possible that the main unit is looking for the device in order to complete the setup.

I would, however, first check to see if the behavior follows the device when you are disconnected from your local wireless network. If you connect to a cellular connection, does the app respond correctly?