What are the settings on your router?
Have you confirmed that it is working as a DHCP host.
Is the network SSID being broadcast or must it be entered. If so enter it from the network name page.
Sometimes all that the DVR needs is for you to start the naming procss and then the most recent previous name will already be in the in the name field if that is the case, simply accept.
TiVo S2 245 Hrs; S2 DT; S3
Mixed Wireless/Wired Net
Mac G4 867 OS X 10.4.9