Activating Device...hanging

I have a doorbell 2, connected to fibre broadband which is normally 30Mbps to 155Mbps, close to a wireless access point, and connected to mains power. Regardless of where I connect from 4G or fast wifi, I often get the message "Activating Device" when trying to answer the doorbell or to go into live view. Any idea what's causing this please? My firmware is up to date, signal strength is RSSI-42 and Live View is set to on in the device settings. Many thanks, Charlie.