I have an iPhone 10s and if I am away from my wifi, I cannot get any apps to work.
Weather station, home security, TV, garage door-you name it. They will not work. Trying to watch a video from my security system, it will just buffer and buffer and buffer. When I am on cellular data I cannot use my apps. My phone works, my texts work, but apps do not. Once I am reconnected to wifi, all apps work ok.