Can't connect Nest Protect (gen2) to BT Smarthub 2

[lynetter]

Has anyone successfully managed to get Nest Protect to connect to the Smarthub2?  On the Nest forums they seem to be suggesting the problem is with BT's settings but I don't know what to change.    https://www.googlenestcommunity.com/t5/Nest-Protect/Replaced-my-router-with-a-BT-Smart-Hub-2-on-fibr.... 

I'm starting to wonder if I need to buy another router but I don't know what is compatible .. It all used to work fine with my previous network - it only stopped connecting when I upgraded to BT Halo (specifically FIBRE WITH HALO 3+) and in the process was forced to accept the Smarthub2. I managed to get all of my smarthome devices (hue bulbs, alexas, google home, nest thermostat) connected to the new network BUT I have never been able to get my Nest Protect back up and running. I was determined to crack it today and so tried everything that was being advised... . I went into the Smarthub2 to turn off 5Ghz to ensure that it was definitely 2.4Ghz; I factory reset the Nest Protect (many times); I restarted my phone; I reinstalled the Nest app; I tried using the Nest app to connect both on a Pixel phone and an iPad, I checked my connection was iPv6 (which Nest Protect requires); I sat next to the Smarthub while I was trying to connect the Protect...  all to no avail. Any ideas gratefully received!  Thank you 🙂 

[imjolly]

when you turned of the 5ghz network did you also select the 2.4ghz wireless channel manually instead of leaving on auto?  I would suggest using s wifi analyser on your phone to see what networks are near you and channels in use then select a free or less congested channel.   you can also try changing the wifi mode from 1 to either 2 or 3 to see if that helps