I'm trying to install an HS220 smart dimmer switch. I join the switch's temporary wifi network, which works, it then asks me which home wifi network to join, however once I select the network it just says it's attempting to join the home network. See attached. 

This eventually times out, and it suggests I reset the switch, which I do. But the same thing happens every time. 

I have about 35 Kasa smart switches in my home and this is the first time something like this has happened. Is my device defective, or is there some way to salvage?