Companion app does not connect to iPhone x

After opening Zwift on my iPad Air 2 the Zwift Companion app doesn’t connect on my iPhone X.

Both on same WiFi, have rebooted, gone into flight mode, all no help.

If I open zwift on iPhone X, companion launches ok on iPad, so does work that way around

Any advice please please

Is this at home or a public WiFi?

WiFi isolation could be the issue here.

Hi, yes I’m using home WiFi