I keep getting DOS attacks?

Since you are being bombarded the router is understandably overloaded and bogged down.

If you do not have extremely secure wireless, it is time to change. Reconfigure using WPA or WPA2 encryption with a very strong preshare key (at least 12 characters, mix of numbers and both upper and lower case letters plus some symbols that do not spell any word) and invoke MAC address validation. Be sure to list the MAC address of wireless interfaces of pcs you want to connect in the MAC validation table of the router. Change your SSID to something unrecognized by others. Reconfigure all pcs you wish to permit to access and then shut off your SSID. Once this is done hackers will go elsewhere as you have eliminated them from using your system.

If the DoS attacks happen after wireless is properly secured, then it has to be comming through the Internet feed. The router can handle only so much before it shuts down to disrupt the DoS attempt. However, there is another solution to this. Shut down the router and leave it off in the "late evening" when the attacks happen. Once the attackers find it down for several days in a row they will go elsewhere.

1) Has he restarted his router/modem to change his public IP - Try leaving it of for a few minutes? (Virgin Media use sticky IP's - If you use the virgin superhub, put it in modem mode and connect a external cable router what will change your public IP - Once your IP has changed you can revert it to normal) 2) Are any computers on his home network Infected? - This may mean that when his public IP address changes, it is tracked. In this case run several anti-virus and anti-spyware software at their highest level. (Avira and Spy Bot S&D are good free ones) 3) Has his local network been hacked, Is his wireless secure using WPA2? - He could be getting attacked and tracked through a breach of his local network.