If your hub won't add, but the top and bottom indicator lights on the hub are on, we would recommend checking for the following; if you need assistance with checking the following, please contact the maker of your router.
a) Assign the hub's MAC address a static IP address via the router's settings. The hub's MAC will begin with B0:CE:18
b) Confirm your router produces a 2.4 GHz WiFi network and make sure the iOS or Android device you are doing the setup from is connected to the 2.4 GHz WiFi. Although it is not always necessary, you may want to consider having the 2.4 GHz WiFi and the 5.0 GHz WiFi broadcast as two separate WiFi networks.
c) Ensure all of the router's "ports" are open via your router's settings. You need to open port TCP/UDP 80 and TCP 13000
d) Double-check to make sure your router's firewalls are not blocking the hub
e) Make sure that your Sengled Home app and your phone's OS are up to date