You can set up the WiFi via CGI command from a web browser as a work around. Note the special handling of certain characters in the password (red arrow).
It turned out to be the hash # character in my Wifi password that prevented the Ezlo mobile apps from successfully pairing the VistaCam 1103 to my Ezlo Secure.
As such this VistaCam 1103 is still paired to my other Guest wifi instead.
Strangly though the VistaCam 703 did pair OK to my regular wifi with hash in the password and to my Ezlo Secure. So only seemed to be an issue with this particular VistaCam 1103 model.