Thanks for your help, I will give it a go and report back.

Double check to make sure you've got your gateway addresses set correctly. If it works when you're plugged directly into the cable modem but not when it's plugged into a switch/router it may need to have the gateway address set differently. It depends on the configuration of the router too.

Gateway should be set by DHCP which seems to be working correctly.

I think I am going to re-install everything this weekend - I have just put my PVR250 into the box and all I get is a black screen when I try to watch live TV. I really need a how2 for Via M, PVR250 and R4V5. The Via how2 on knoppmythwiki is good but basically not good for a novice like me who does not know which bits to change for the slight differences in hardware and software.