Numpad issues

Hello, me and my friends is currently playing Garry’s mod over LAN.
But we’re having a problem right now, for example when my friend puts out a thruster I can use it too, can we change this somehow?
I mean we will have loads of problems if we don’t fix this :(((
Thanks in advance,

Check that sv_lan is set to 1 before the map load, or set it to 0 so each player has a steam id assigned.