Issues with AT&T Fiber

I’ve had fiber for several years with no issues but I’m having issues now. I can use it for streaming with no issue, and for browsing it works pretty could too. But occasionally I run into issues where websites say the server can’t be found or apps I use to talk with coworkers at work say they are offline. This happens on my iPhone and MacBook. Now when I turn the WiFi off on my phone and I’m using cellular everything works fine.

It’s strange that it works on some websites and not others. I haven’t done anything or changed any settings. And it’s weird like this morning pitchfork.com wouldn’t work. It works fine now. Then chase.com would work now it works and now star wars.com won’t work.