Does it just spin? You have to counterhold the other side with (what I recall is) a 17mm wrench. I think the nut you remove may be 18mm.
Also, the top bolt of the drop link is what holds the strut on so if you are swapping drop links you should put a jack under the carrier to support it, or it may slide down the strut.
Edit: here is a video (that I haven't watched so don't know how useful it is) but it may have some info for you:
https://www.youtube.com/watch?v=v-voasQA17A