Why Do I always have poor connection when I play Call Of Duty?

This occurs alot, I have moved rooms with my brother and the router used to be in my room ber since Ive but now ive moved rooms it just lags whenever I play call of duty 4 and any other cod game! I always get 2 bar connection and bullet lag everytime! It proper annoys me, Is there any way you could stop it any ways of making the connection better for gaming? Thankyou:)