You should have in the npcserver if someone puts a npc thats going to disconnect the server it will give them a message like 'Unable to creat npc Reason: The npc code you have entered contains inproper scripting which can cause the server to lag or disconnect. Please go over the script and try agin'.

Their should also be a thing where every houre the npcserver checks if it's connect, and if it's not it will auto reconnect.