Do mirrors really help

So I'm kinda sick of being invaded i recently just started this game only have 30 hours on it so far but it seems like even using a mirror doesn't stop from someone invading when I'm trying to specifically do something and it's always someone like level 400 plus absolutely grinding my gears. Maybe it's my game or something but even using the mirror doesn't help and I can't play offline with what I'm trying to accomplish. Sorry to rant it's just annoying getting ganked 25/8