Internet Connection Problem?

[Carlos M]

Many things can be the source of this problem.

Check if your sisters computer does not have softtwares like eMule, or if it is not downloading something that is using greatest part of the band.

Other possibility is that you have data loss between the router and your laptop.
If your connection is via USB, check if the USB cable is long. It should be as short as possible. USB cables of 1.5 meters ( 5 feet) are sometimes source of loss data and make the internet connection become slow. Check also if the USB cable dont have bad contact.
Sometimes I need to clean the USB contacts. If they are dirty they produce loss of data, and the connection become slow.