IP68 Ethernet Gland for Outdoor Enclosure - Size M25
Amazon.com: CNBTR RJ45 Coupler Underwater Ethernet LAN IP68 Cable Wire Connector ion M25 Gland No Shielded Double Cable Use for Outdoor LED Equipment Pack of 5 : Electronics
Cable Gland - Waterproof RJ-45 / Ethernet connector [RJ-45] : ID 827 : $7.95 : Adafruit Industries, Unique & fun DIY electronics and kits
More Choice of Cable Glands From Single Source - Optimas