It is probably my own fault
Yes, I bought a Dyson air purifier - basically a Dyson fan with an air filter around the base air intake (the first generation Hot and Cold one). And there is an app that allows me to control the fan and the temperature and see what it thinks of the air quality in the room.
Or rather there was. Until there was an electrical storm which fried my BT 'Home Hub', so I needed a new one with a new WiFi password. Woe is me! I cannot for the life of me get the app to connect to the fan and tell it the new WiFi network name and password. "Simple!" I hear you cry, "download the latest app version from the Apple Store and you'll be fine." Oh, but I have an old iPhone 7 Plus which cannot use the latest app as it runs on a later iOS than available for my phone.
Like I said, probably my own fault (although I totally deny any and all responsibility for the electrical storm).