Devices say connected but internet does not work (on some devices)

I just got xfinity internet and since day one I’ve had an issue of being on my phone, smart tv, and computer all at the same time, but when suddenly one, or multiple, devices will say they are connected to the internet, but when I try to use internet, it does nothing. Yet during this time, other devices will work perfectly. As of right now my computer and tv work perfectly while my phone says it’s connected, yet it can’t use anything involving internet. After some research, this appears to be far too relevant of an issue to not have been fixed yet. Does anyone know of something that causes this or just anything I can do to fix this issue?