A friend I play with seems to think that every time I play with him on Call of Duty Advanced Warfare that his connection becomes crap. My XBox is using a wireless connection and I have tested my connection with the network statistics option they recently added. My ping always registers below 100 and I have no packet loss, so I don't really think I should be affecting his performance. He claims that every time he tries to shoot someone when we play together, he gets hit markers, and that when he plays by himself he never gets them.

So is he right? Is my so called "crappy wireless connection" really affecting his game play, or is he just imagining it?

I need some answers from network experts, so I figured what better place to get them than here?

It's a common misconception that so-called "high pingers" are ruining everyone else's connection. The server, if it is properly written, does not care if a player has 1000ms latency while another has 20ms latency, its internal authoritative game state is independent of the player's respective latencies, so if there's a player with a high ping in the game it should not affect other people's connection quality.

What is true however is that it can be frustrating to play against someone with a vastly higher (or, correspondingly, lower) ping than you, because (if he has a higher ping) he doesn't update his position/velocity information with the server very often, which causes the network interpolation algorithm to be very inaccurate, making the guy rubberband all over the place and generally being hard to hit, or (if he has a lower ping) your actions are so delayed compared to his that by the time your "shoot in this direction" action has reached the server, the guy has already moved and shot you back (but it doesn't look that way on your screen as the server hasn't had time to send you the information yet).

TL;DR: it can be problematic to play against someone with a very different ping from yours, but unless the game is really badly implemented, the mere existence of a high-ping player somewhere on the server does not cause everyone else's ping to suffer