have you split the networks in your hub ensuring that 2.4/5ghz have different SSID
Did you sort your issue? I've just bought some Sonoff plugs today and am having the same issue !
Hi there, I just found the info below on another website for a similar sonoff product. I have a BT SMart Hub, so will be doing this sometime this weekend ! Bit of a faff as will have to connect to my BT Hub via ethernet to do it - the wifi is currently disabled as I have the wholehome. Looks like a bit of a faff, but worth it...
"The slight pain as someone else mentioned is having to disable your 5G WiFi network, i have the BT Wholehome system and you can't disable the 5G. Had to turn that off completely and enable the 2.4G on my Virgin router and duplicate the Wholehome network name & password on that. Connected them all to that network and then disable the Virgin router wireless and restart the Wholehome one and it connected perfectly."
Thanks BrunoN for adding the link.
Despite sounding quite complicated, it took me max 10 mins to use the renamed router network to set up the devices and then revert everything back to how it was.
It's really bizarre that the devices can see the 2.4ghz network in routine use, but not when being set up.