In reply to a post by brettuk:

I thought the other posted said they run CAT5, is this not the case?

I always thought it wasn't but good quality phone extension cabling. Glad to be proved wrong

but with RJ45 terminators, rather than ethernet?

RJ11, you mean?

Even though it is a Cat5e cable (with RJ11), it will still lose more used as master socket to modem extension cable than exactly the same cable (with RJ45) would as an ethernet cable between the modem and the router.

That loss may be a worthwhile tradeoff depending on other considerations. I don't have a feel for the expected loss as a modem extension cable; there should be effectively no loss if you use ethernet to separate modem and router.