There could be a number of different things that could be causing it. Resetting the modem isn't going to be one of the solutions. Some examples of what could contribute to the problem:
Without more information, it will be extremely difficult to identify the problem or possible solutions if any since a number of the issues are beyond Telus' control.
Consoles are whole other issues. Is your PS4 on wifi or is it connected using ethernet? 200mbps sounds like wifi to me. If it is, there are many environmental factors in an average residence that can and do affect wireless performance. Wired is always best. With the PS4 it's a lot harder to diagnose issues on the connection between your house and the game server.
Have you tried Googling PS4 and COD lag issues? There isn't a shortage of results. One version of COD on PS4 is known to match players based on skill rather than latency. That can easily have unexpected performance results. Recently other players have been reporting random lag spikes in COD as well.
You'll also want to test the speeds from your PS4 and not using a device near it. They can have very different results. Same goes for latency. How are you testing that?