Thanks John.

The router (a Thomson Speedtouch) was initially set to 192.168.1.x. with the subnet set to 255.255.255.0

This is a tricky little router which is buggy. I can't change the router subnet mask by logging in, due a known bug. Instead I have to down the config file, open in text edit / note pad and find and replace the 192.168.1 with 0. Then replace it with the original file (.ini). This does work, but at the moment I have the router set to 192.168.1.x and 192.168.0.x - which I suspect I need to delete the 1.x so it runs just off of 0.x.

I'll give this a go.

Is there a way of finding the subnet mask on the Tivo?

BTW - Tivo is at my in-laws place, so I'm only getting the chance to work on it when I get up there at weekends.

Thanks for your help so far.