Well, given that the hole is made for 18/3 or 16/3 SJ cord, typically, they don't crimp tight which is why I mentioned Duct Seal. An RJ connector, let alone one with a WP housing on it won't fit through it. Lowes and Home Despot may, or may not depending on local demand and inventory, have them in stock. Amazon may be a better choice or a real electrical supply house.