Channels missing when using Xfinity app

Recently I have noticed that many of my channels are missing when I attempt to watch tv using the Xfinity app. When using a tv that is wired with a cable from the wall all my channels are there. But if I attempt to stream using a smart tv, phone or kindle they are not listed. It is just normal channels that most people have that are missing; espn, amc, tnt, ect. I recently had my modem replaced by a comcast tech. I'm not sure if the 2 are related.