Packet loss and huge latency spikes

I have the 600mbs download and 30mbs upload plan with the Xfinity xfi gateway motem and I’m constantly having packet loss issues aswell as huge latency spikes . I was wondering if I need to change routers to fix this issue as I’m a competitive gamer I depend on the WiFi and it seems to be failing me at my time of need. My apartment only allows Xfinity so could it be something to do with congestion ? I’m looking for any solution this and open to any ideas . I’ve reached out multiple times and I do not want to have to pay to get someone sent out to my apartment I just want to be able to play my game and stream it and I can’t do either let alone both at the same time without having serious issues .