Is there a way to protect my privacy at the router level?

So something really strange happened to me over the holidays. I'm running Linux on my computer with a whole bunch fo tools and utilities outlined at privacytools.io all aimed at protecting my privcay.

The problem was that I had family over the holidays; I quickly grabbed my sister's phone (as it was closest to me) to check out a quick story at the New York Times. Rather distressingly, I found an ad on her iphone (no adblock) that was relevant to me. There is no way she would ever get that ad...and I felt quite guilty that I had compromised her privacy by forcing her to get ads which are relevant to me (even though I thought I had blcoked all those features).

So what can I do to protect myself and all those who visit my home in the future? Can anythhing even be done? More importantly, I'm not that adept with computers, so I'm looking for a rather layman's guide.