DNS isn’t resolving server names???

I have tried everything that I could find and would appreciate the help so much but for a month and a half I’ve had dns problems and could temporarily fix is with manual ones or back to auto or even running an Ethernet cord. But at any given point (within 30 mins if I open cod) my Xbox will disconnect all network and my router acts up and kicks everyone off. It worked great for 6 months. Now this, I’ve called my internet and they had me try a few things that all worked out for my internet and made it work again but the second I connect my Xbox x and load up any game (almost all need internet) it’s just a matter of time before I randomly have to fix it again. I’m at a loss and feel like its unfixable because are Xbox s works perfectly fine. Both bought brand new same day same store. Would really appreciate any help I need it fixed before Diablo 4 drops cause I pre ordered… hope I don’t miss out.

:)