It is dropping, last time i've found it was after more than a week of searching on a new server.
The ISN is designed to be accessible at endgame content -- It's all about your luck in the end.
If you really don't want to wait, or if you want to setup a trade post, make it spawn with a chat command.

ahh okej i see then i understand ^^

May I ask what is the chat command?

Hi Piti Viers, first of all, many thanks for this great mod created.
my issue is that since two weeks ago, I can't find NAC on my server online, it was wiped twice and accelerate respawns of hidden places in order to find NAC quickly (just for testing), but my friends and myself aren't able to find it, even on a dedicated server (LAN).
According to your mod, it seems NAC will repace some three guides, I added more percent of coincidence on mentioned guides but still same, unable to find this and I would like to avoid to spawn it using chat command.
By the way I'm using my own mod for stacks and respawns, maybe it crash NAC respawn, I don-t really know.
Hope you can help me.