iOS live view

Door bell is set up and working, but will not show live view on iPhone or iPad keep getting activating device. Yet if I connect on my desktop pc which is on the same network, via Alexa show or the google app it works. Also if I switch off WiFi and just use cellular on my iPhone it works in about 12 seconds. What is going on is there a problem with iOS app. Signal strength is extremely good. Fed up with it.Any help would be great