[Answered ]-How to get the MAC address of client

MAC address isn’t preserved during packet transferring. MAC address is used for routing in L2 network segment (aka subnet), which is pretty small: Local Area Network may include several such segments. For packet passing through multiple L2 segments (hops), it is transferred by chain of routers, each one sets “source MAC” value to self address, “destination MAC” value to next router’s MAC. So packet, received by server, has “source MAC” set to the last router’s address unless client is in the same subnet.

Also JFYI MAC can be easily changed on PC to any chosen value.