This Kasa HS100 was set up and working correctly, but was the only TP-Link device that didn't appear in Google Home when I linked TP-Link to Google Home. So I decided to remove it from the TP-Link app and re-add it as a new device, hoping that it would then appear when I linked TP-Link to Google Home.

Having removed it, I tried to reconnect it following the 'Add new device' instructions. The app was able to detect the HS100 and connect to its wifi network, but once the 'Connected' message pop-up disappeared, the 'Connecting to device' screen continued until it timed out (with the HS100 wifi still connected to the mobile).  

I've tried all the troubleshooting tips, disabled the VPN, rebooted the mobile and the router, reset the HS100 to factory settings, tried the app on a different mobile, but always get the same result - the app connects to the HS100 wifi network, but times out without configuring it. 

As I said, this HS100 had previously been configured, connected, and working OK on the same network with the same hardware and software...

Any ideas?