Is the laptop setup as a static address or is it getting DHCP? Another thing you can check is if the port on the router is working or if it is in another VLAN.
Another thing to consider is the Auto Negotiation on the Switch to which the 520 is attached I have had to hard set the Speed and Duplex on the iSeries before with some switches models. I would also make sure your Lan Console Subnet is appropriate you want to have it closed as much as you can. Check your Routes by using CFGTCP option 2 making sure your default route is set.