You can fix your internet all you want, and spend millions on hardware and internet speed. You still will get lag connections because it is a player-to-player connection. Both parties need a solid connection to have no lag, it is not based off your connection alone. This is why lag-switching and other "cheats" are seen through the game. With a good connection your movement is fine and your moving normally on your screen. Your opponents poor connection will show you moving fine on their end (due to your connection), and them moving fine on their screen. Yet due to the poor connection they are spamming buttons that is sent slowly to your system. That is why players will randomly "teleport" and shoot you on your screen. A dedicated server makes lag affect the bad connection players only due to both parties only communicating with the server and not each other. This will have the person with a poor connection have a small amount of lag but still be playable. There are thousands of video games with dedicated servers where you will only encounter lag due to your connection and it will not effect other members of your game lobby. It is Bungie's "problem" since they have a player-to-player connection and never made or announced a dedicated server. They do ban/punish players found of "cheating" but it's hard to determine "cheating" due to the player may just have a crap connection. It also is a slow process to actually ban/punish players if they draw enough attention to them.