hey guys looking to help my parents out.

they pay for 20Mb connection however due to where we live we are unable to get that sort of connection. in my household we have 3 xboxs, 2-3 netbooks, a tower computer and 3-4 smart phones linked via wifi. now when im on xbox i disconnect my netbook and phone from the network. now when someone uses the network, most common example is my brother on his phone, it destroys my online game. how can one little device kill my connection that bad. often he is on youtube via his phone. which i know can cause lag due to the phone loading the video but surely it would not require that much Mbps to load videos. i could understand if it was maybe the netbook cos that is a fairly powerful network device but a phone. is there anything that can be done to this. my main priority is trying to cut down how much my parents are paying for the connection seeing as we aren't getting that connection. im getting to the point of changing the network key and holding it ransom so if they want to connect to the internet i have to manually put it in.

any help would be greatly appreciated.
Jac