The thermostat must be setup and connected to a Wifi network with an internet connection at least initially. Once setup, it can lose its network and you can control it manually from the thermostat.
A workaround here would be to use a Wifi hotspot on a phone or tablet. Note you will need 2 devices to set this up.
@MHO1968 just one quick final check in here since activity has slowed down. We'll be locking the thread in the next 24 hours, but if you still need help, we would be happy to keep it open. If there's more we can do, just let us know.
I appreciate the help, davidking and Jeran.