Every internet ad talks about download speed. Gamers rarely look at the upload number, and that is a mistake. Every keystroke, mouse click, and controller input you make has to go up to the server before anyone else in the match sees it happen.
In a shooter, that means your shots register based on what your upload delivers to the server, not what your download brings back. If your upload is choked — because you are backing up photos to iCloud, streaming to Twitch, or sharing your connection with a video call in the other room — your inputs arrive late. To the server, it looks like you are always a half-second behind. To your opponents, it looks like you are terrible.
This is why cable plans that advertise huge download numbers but only 10 or 20 Mbps up frustrate serious gamers, and why fiber plans with symmetric upload feel so much snappier. If you want to see exactly why upload matters and how modem type factors in, take a look at the Mediacom article on how internet speed affects gaming.
