Lag

I’m currently experiencing issues with my Xbox one s with lag , it was completely fine with cod vanguard now mw3 it’s laggy , it’s not unplayable but seems loss of bullet reg in long range gunfights , jittery with quick movement , objects are part complete until I run towards them it’s all a bit annoying ! Im wired to the router I’ve reset everything and nothing seems to work ? I’m currently on a 500mb package with bt and I’ve checked my connection and I have 0 packet loss . I’m thinking of buying the Xbox series x as I’ve just had enough but don’t want to be £500 out of pocket with the same problem Thankyou for any help

:)