A simpler solution that worked for me...
Connect to Hub (Hub 3 in my case). I had 2.4 GHz and 5 GHz enabled. Click on Disable 5 GHs and Apply Settings.
On my phone, which was trying to connect using eFamilyCloud, disconnect WiFi & reconnect.
Connect to bulb on eFamilyCloud.
Connect to Hub. I had 2.4 GHz and 5 GHz enabled. Click on Enable 5 GHz and Apply Settings.
On my phone, which was trying to connect using eFamilyCloud, disconnect WiFi & reconnect.
This gets your Hub back to exactly where it was before. The eFamilyCloud connection seems to avoid any connection that has 5 GHz even if it also has 2.4 GHz enabled, but once you have set the connection up, it doesn't seem to worry. It's a bit weird, but it is not the hub's fault: it is doing what it should as far as I can see.