This mod does one thing and one thing only, it prevents wandering traders from spawning in a 5x5 chunk (default, configurable) area that has a no soliciting sign (any vanilla sign with the words will do).
Mod works serverside only so it's not required on connecting clients, but it can still be used in singleplayer.
Discord: https://discord.gg/vZxnfa4
The No Soliciting Team
