Xfinity Internet not allowing me to play online on my PlayStation !!!!

My connection works great for every device in my home: phones, laptops, smart TVs, all work without a hitch. My PlayStation 4 connects fine through Wi-Fi and I’m able to watch videos and netflix and download apps from the store. However, every time I try to play a game online (typically Modern Warfare) I either cant connect or always get booted from a match after a few minutes when I do finally connect. I can’t stand it I’ve had to problem for almost a week. I tried to talk to a agent but it doesn’t allow me. So I can’t do anything about it someone please help me .