Yes I'm sure this is likely to be the reason.big_dirk said:
Why did the range of addresses your router is supporting change? You will need to change them back to the ones in use before that were compatible with the ip address and the ip gateway address you set on your Tivo using the nic_config_tivo command at the Telnet prompt.
You won't be able to get access to the Tivo until your router is changed to addresses the Tivo is compatible with. Otherwise you will have to pull the drive and change the IP addresses in use on the Tivo drive to ones compatible with your router by reconfiguring it while attached to a desktop PC and using the Silicon Dust cachecard card configuring CD.