Constant internet drops

Hello,

Ive got a Macbook Pro (late 2011 I think) and after updating to El Capitan Ive been experiencing constant internet drops. I only have this problem on this Macbook, not on my other Macbook Pro (2015). Wifi is fine and stays connected but the internet drops some times as much as every 5 minutes. Turning wifi on and off fixes it. Also waiting 30-60s seems to work.

Does anyone know how to fix this? Its becoming quite annoying to turn wifi on and off every 5 minutes.

Thanks for any help!