Hub 2 cannot connect 2.4ghz to WiFi heating

[#1]

Hi
I have recently moved house and have a hub 2. The landlord has sent me information to connect the WiFi heating and air conditioning to the app (supply master). I have gone into the settings to turn off the 5ghz band to connect the app and it keeps timing out (it says it does this with 5ghz). I have tried changing the other settings on there too but still can’t seem to connect to the WiFi.
The landlord suggested linking to just the 2.4ghz band but I believe you can’t do this with a hub 2?
Any help would be so much appreciated as I have been trying for weeks to get this to work.
I have even used the WiFi extender and turned off the 5ghz on there but still no luck. Thank you

[#2]

@Georgiaj If you have disabled the 5Ghz band on the router, then your heating/aircon can only connect to the 2.4 band - it must be something to do with those facilities - but I don't know what, I steer clear of 'connected home' technology.

[#3]

@Georgiaj Welcome to the Plusnet Community Fora.

Can you obscure any personal information and post the required settings here so that we can see just what is required?