I FIXED IT!!
I had to set all parts of the npc to owner’s network to be nil, and to make the error not appear, every time root part anchors, script will set the required state!
for _, part in pairs(NPC:GetDescendants()) do
if part:IsA("BasePart") or part:IsA("MeshPart") then
part:SetNetworkOwner(nil)
end
end
Thanks to everyone who at least tried!