If you do want external access it can be done for free using DynDNS and a script running on your Tivo (i.e. without your router directly supporting DynDNS).
Needs a few utilities but all the leg work has been done.
Details at the other place /forum/showthread.php?t=51840
Needs a few utilities but all the leg work has been done.
Details at the other place /forum/showthread.php?t=51840
