Converting RJ11 sockets to RJ45

Hey all, not a career or coding related question, but figure I might find an answer among other people into tech living in Ireland.

I want to switch my RJ11 sockets for RJ45s since I found out I have CAT5e cable running to all of them. I have 4 sockets but I found 6 cables where they all terminate in my utility. I really only need to connect two together to add an AP upstairs from the router downstairs, but how would I find out what the other 2 cables or for or where they go?