Network problem

Hi everybody ! I have a problem while playing forza 5. Everytime i play forza 5 it tooks all the network power, i can’t even send a photo on whatsapp, until i close the game, also can’t share screen on discord or do anything that does need some network. I have a really good internet speed , that s not the case, but i can not understand, my friends are not having the same issue. Is there anyone that knows a solution? Thank you.