Wifi Doesn't Work but Works Fine on iPhone?

[iPowers]

When I am at home, the Internet works fine. The worst that happens is it lags to load for a sec and then shows up, but easily managable, but for some reason, every time I go to my parents' place, the Internet will not work on my computer. What makes no sense is if I use my phone, it works fine, and when my parents use their computers, phones, smart tv, etc., it works completely fine.

Has anyone been through this issue before and how can I fix it?

I have a MacBook Pro (mid-2010) running the latest version of El Capitan.