This is usually a network issue. Make sure that you are not using wireless networking for your computer. Double check your network settings, cables, etc. Try connecting the printer directly to the computer - make sure that you set up the IP addresses appropriately. If the problem persists, the the problem has been reduced to the computer network interface, the cable or the mainboard on the computer. If the problem is resolved, the you need to look at the network - router, switches, cabling or possibly conflicting IP addresses.
Good Luck