If you can find out from your DHCP server what IP addresses have been assigned to your BT Discs. Once you have that, you can try and navigate to one of the IP addresses instead.
Hi again, I see it’s a slightly more complicated web config than they have for the Home Hub. You can disable 5ghz in an obvious way on that. But it’s not very clear on the whole home web config. Do you happen to know the process?
The hardware is the Whole Home WiFi Premium kit, if that helps. It auto updated the firmware at around 1300 today.