Have you enabled DHCP on the router? In a windows command Prompt type IPCONFIG /ALL, enter.
You should see you IP Address as 10.40.248.nn to match the router. If you see 169.nn.nn.nn then you're not getting an IP address from the router. After Enabling DHCP in the router, type IPCONFIG /RELEASE then IPCONFIG /RENEW in your command window. Hope this helps