If you look through your router setting you should be able to find a bit called MAC Filtering- you could try that. Get your PS3's MAC Address (found in the system settings) and go into the mac address filtering in the router set up. If there is a button to click to enable it click that, then put in the MAC Address of the PS3 in the blanks provided. Once done hit the button for saving the settings.
If all else fails you can try contacting Sony's support and they should be able to walk you through it.
I tried to get hold of the user guide from the manufacturer's site but was running into errors of some sort with DNS (possibly blocking downloads from outside their region) so i can't provide exact details on where to go.