im using LAN to play LFS with my friends,then, they connect to my pc, which i hosted the lfs using local area, then. when they already enjoyed playing, suddenly the (lag <time in sec>) comes out of their car and the car dissapear ( that one is common) but usually, when ppl play LAN,it doesnt have any laggness,but i dont know what happen, and then my friend will be timed out and have to reconnect, any solution to this problem?

im using Linksys Router and Linksys HUB

Try using one of the other PCs as the server and see if you can reproduce the fault.

i tried using other computer, still the same,is it a bug or my computer problem?i play other LAN games also i dont have any problem

LFS uses UDP packets to report positioning and so forth. UDP packets are not guaranteed like TCP, but don't have the overheads. What most games do is to fire as many UDP packets, as fast as possible to ensure that the data gets there.

Now I believe that MotoGP3 uses TCP for its networking, so packets are "guaranteed" to arrive (they are resent if they do not). In situations where there are damaged cables, or a faulty switch exists, packets can become lost - even on a lan.

In short, the first step is to check your cables and connections.

Good advice Karl, also I would add that network card failure (including intermittent faults which can be hard to diagnose) is quite common. NICs are cheap to replace though, thankfully.

i think theres no problem with my 8 pin wires and my network card,,we renew it every month,but yet still, im sad =|