well that's just the way it is dude. Obviously someone on another computer using the same line is gonna eat up bandwidth. There isn't much you can do about it. Either play when no one is on the computer, tell them to get off or upgrade to faster internet that wont slow down as much when being used by more than 1 device.
there are 6 computers in my house, including laptops too, and most of the time 3 of them are being used at the same time and i never get any lag. what i would recommend is getting a better connection dude, that's all there is to it.
I have this problem now too.... was fine for almost 2 years but starting the beginning of September if some1 just opens a web browser i get mad lag on xbox live....called my ISP they told me it was my router..my internet speed is fine...dunno if i should get a new router or what, i have all the correct ports opened to a static IP....dunno what to do anymore...
First off, what kind of internet connection do you have? Are you using your own router, or one provided by the ISP? One thing you could consider, if you're unable to get a faster tier of internet speed, and/or want to try to solve the problem a little more elegantly, is to get a router that supports some form of QoS, and have it provide priority for traffic going in and out of the console(s). That may not solve *all* the problem, but it should go a fair way in mitigating the perceived lag that you get in the actual games.
if theyre on a forum, like gamespot, make sure they turn off signatures so they stop loading all those pictures that lag up your 360. in the end if you really want it to be fixed youll have to upgrade your internet. but games like battlefield which EA hosts the servers, you wont lag on no matter what, so u might want to buy BFBC