I've just plugged in my new Spark Smart Modem, replacing my old ASUS RT-AC68U which has well and truly done its dash. Setup was super easy, and I got my Wi-Fi networks (main and a couple of guest networks) up and running, no problem. They're working perfectly. However, I also have two things plugged into the ethernet ports that just aren't connecting. One is my Vector Sungenie solar system, and the other is an ethernet hub that lives behind my TV and provides the internet to my AppleTV and home theatre system. Neither of them are connecting. I've tried restarting the modem and switching the ethernet cables back and forth between the ports. They are properly seated. Did I do something wrong? Am I overlooking something obvious? TIA.

Edit: SunGenie has randomly connected. AppleTV still not working.