I'm looking to upgrade to the Home Hub 5

Is it possible to use a RJ45 cable from the red WAN Port of the HH5 to the filtered faceplate on my NTE5 socket. Reason i'm asking is that I have a 20 metre Ethernet cable going from my Openreach modem to my netgar router.

I want my HH5 where my netgear router is because it's connected to my USB printer which is shared over the network.

I'm looking to get rid of the BT openreach modem because my 2 year old son keeps messing with it and switching it off.

Can I use a RJ45 to RJ11 converter if it's not possible?

No its RJ11 to RJ11 if you are using the internal modem.

As for the converter, no idea.