Intermittent loss of internet and functions

I have an iphone Xr that worked just fine four days ago. Now intermittently the internet becomes unusable, apps don’t update, texts and sms messages don’t send. I’ve closed the apps, turned both the wifi and cellular on and off, reset/shutdown multiple times, I checked the battery life and was at 88%. There’s a bar or more on my internet, and the charge is good. I downloaded the newest update. Still it does this. What else can I try?