High ping during online gaming and I demand answers.

I'm an online gamer. I got Xfinity internet because their plan for really decent speeds was cheaper than my previous isp so I made the switch. Also, my previous isp was terribly unstable when gaming online. So, I spoke to a few customer service reps who told me switching to Xfinity would fix my gaming issues. HOWEVER, I have my Xbox series S cat6 hardlined directly to the cable gateway in the next room. When I play Apex legends I constantly have packet loss icons at the beginning of every match. When I play halo infinite (although better than my previous isp) I still get huge lag spikes and unstable jitter. When I play COD modern warfare 2, especially the battle royal mode, it's unplayable. I've had one or 2 matches with a stable ping of 60 to 70 which is still incredibly high considering my server is a 20ms ping away. Other than these 2 matches that were incredibly laggy, my ping has been wildly unstable between 100 to 250ms ping. Try to play a competitive game with a ping that high, it's impossible. I noticed that if I play at 3am east coast time my ping seems a but more stable,  still high but stable at least. And packet loss so bad other players in the game literally dissappear in front of my eyes and reappear someplace else. I joined Xfinity because I believed I was getting a stable quality competitive gaming connection across all games and its simply untrue. So, why? I've had customer service reps look at my connection and say everything is fine. Why is my ping high on every game I play? Please advise.