Then the following question would be , who is the server owner ? ( is it your friends server , or did he decide to play on this server and invited you to join him , on an unknown server ? )
for what you describe , there is 2 possibilities , or the server you play on has this bug where all npcs teleports to the 0.0.0.0 location , or it’s the server admin spawning them on top of your base ( maybe there is a discord , or rules ( as there is generaly on private servers ) that you may not have followed not knowing them … )