Lenovo Ideapad z580 Internet Issues

My brother bought one of these laptops, and it impressed me enough to purchase my own in June. I live in a bungalow, with the wireless modem located in the office in the front of the house, with my bedroom nearer the other end of the house. I can use the laptop online no problem, in areas close to the office. This is understandable. What I can't understand is that I cannot use the laptop in my bedroom to do even simple tasks, like go on Google, when it claims to have a 2 or 3 bar connection. My brother can go on Youtube on his laptop, the exact same model, with no difficulties. He's never had an issue, mine seems to be getting progressively worse