First, I have checked other forums/questions about this. Tried different solutions like using the wpa_supplicant file, writing a script that restarts/attemps to reconnect the Pi after dropping its connection, tried changing wpa-roam for wpa-conf... and I don't know what else.
The issue, as the title says, is that my Pi will drop the Wi-Fi connection every time my flatmate uses his MacBook. Normally this happens while I'm at work so I don't know if that's because there's a reboot of the router, which usually occurs when streaming a lot of content. (That is why I tried all the re-connection options I've stumbled upon).
I know it sounds a bit vague or even stupid but it's all I can contribute at the moment.
Any suggestions or ideas to this?