MAC filtering is not suggested in the CNET Networking forum. Try this. Try it per the CNET Networking forum suggested router settings.
I have recently purchased a new xbox 360 slim.
It connect to xbox live fine through the ethernet connection.
However it cannot even see the wireless network.
It is within 10 meters of the router and I have computers wirelessly set up 3 times further away from the router compared to the xbox.
I have manually set the ip address etc in as well with to no avail.
When I hit "test connection" it instantly fails, which seems as if it isn't even trying to connect to any network at all.
As well as this I have disabled all security features on my router as well and have allowed the Xbox's MAC address as well.
Please help, any suggestions greatly appreciated.