[Skie]

Bandwidth in games is pretty much updates of x,y and z coordinates of players and their actions. It scales with the number of players, and as Igni said if you are hosting you are receiving and sending all of it to each player, but the information contained in these updates is just a small amount of text.

It's the frequency of the updates that demands a reliable connection. Cables inherent jitter is actually bad for games, so BT's 'fibre', despite being slower for downloads, is usually better for games.