Did you clone your desktop's MAC address to the router? Some ISP's require this, it makes the router look like the desktop from the ISP's perspective. You can check this on the Status page, the WAN MAC sould equal the PC's MAC (seen at the bottom of the Status page.
If you go to Tools/System Check can you ping the DNS server IP shown on the Status page? Can you ping the desktop from the router? Can you ping the laptop from the desktop?