In article .com,
"Rick" says...
Hello,
I would like to extend the coax cable to my cable-modem as I want to
move the latter from the front of the house to the back. I'd like to
avoid going wireless if possible for the moment. I've been looking
around but I don't know what kind of coax I should get (I've seen
maplin do RG58, RG59, CT100 and CT125). Which one should I use? I'm
with Telewest, if it helps. Also, some cable are 75 ohms but others are
50 ohms, which one should I use. Finally, are the connectors that go
onto the coax and screw at the back of the cable-modem F-type
connectors? Many thanks for your help.

Why not leave the modem where it is and fit a long ethernet cable
instead?