I’ve recently picked up some Shelly H&T Plus sensors and unfortunately when I log into the app under “Outbound Websocket” it simply just says “Error !” as per the screen shot.
When I connect to the sensor via the AP then the “Outbound Websocket” option simply does not appear for me.
Has anyone else come across this at all? 
Edit: Solved. If anyone else comes across this, update the firmware of the device. I could not update it via the App. I had to do it when I connceted to the Access Point.