You most likely have a firewall, perhaps Windows. You could allow some TCP and UDP ports. Go to support.tivo.com and search for firewall or TCP, UDP ports.
Original S1 (Recycle Heaven)
Series 2 (PLS, sold)
TiVo HD (XL, PLS, "652")
Juliet Basic (4XL, PLS)
The TiVo Apocalypse begins on Sat 2013 Feb 16 00:00 GMT!