That is a 3g mobile broadband modem. In theory you can get 21mbits with it but you will never get that much. The actual number you get will depend on how strong a signal you get from the nearest cell tower. You are pretty limited in your options you much find a way to increase the signal levels. You could check outside your house and see if it runs better. You also need to contact the ISP and ask them how much signal you should expect to get in your area. You could be in a area that they do not provide the highest data service.