I decided to use an old router with DD-WRT as an access point for 2.4Ghz WiFi and still use the BT Home Hub for 5Ghz WiFi. After over a week of using it I have had no issues with disconnections. I do intend to replace the BT Home Hub at some point.
In my case it seemed the problem was with some/all of my devices at different occasions on 2.4Ghz Wifi network tested on 2 BT Home Hubs that started around January 2020.
Thanks for everyone's replies and help regarding this.