Networking Issue

Hi,

Basically have a router upstairs (where phone line is) cable going to computer and a Home plug plugged into the power socket.

Downstairs i have a 4 computers plugged into a switch with a cable going to the Home Plug.

Easiest way is to move the phone line downstairs to where the switch is i know, but i was wondering if i put a DHCP server downstairs and turn the DHCP off on the router help. I'm not so much worried about internet speed but the internal network speed between the 4 computers.

Any suggestions appreciated.