mobile broadband and dial up connection in order to get internet

here is the problem.. Image: http://s14.postimage.org/t4ri2wnz4/Untitled.jpg i dunno why i need to connect both modem and network in order to get stable and faster speed. if i just connect either one of them, the speed will dramatically drop and the webpage will be unable to load although the connection is still on which mean download or msn was still able to move or on but the webpage...