I am not totally sure of what I did as I did not make any notes at the time. To the best of my memory it was like this.
Log on to Shelly wifi and set the ip as 192.168.33.1. Sometimes after playing with it it will change to 33.2 or 33.3 but it needs to be 33.1.
Can't remember if I left it no the Shelly wifi or switched to the home wifi. Anyway on home wifi I loaded the Shelly app and after a short time it found the device. At first the settings were wrong but could change them easily. Now after being off for 24 hours it is working correctly. Hope this is of help to someone.
A point I am not sure of is if you are switching low voltage devices, how good is the mains separation from the switching side.