BT Business Hubs, Home Hubs etc broadcast a "BTWiFi-with-FON" SSID on both 2.4GHz and 5.8GHz. This is the unsecured SSID that BT customers can log in with through the captive portal.
They also broadcast a "BTWifi-X" SSID, which is a secured SSID which iPhone and iPad users can use to log into BT Wi-Fi automatically (using the connection profile from the BT Wi-Fi app), but it only broadcasts on 5.8GHz.
Because of that, we are finding that the signal is considerably shorter range on the secured SSID compared to the unsecured one, which is a terrible experience when out and about.
I'd like to suggest that BT push out an update to Business Hubs and Home Hubs to enable the "BTWifi-X" SSID on the 2.4GHz band also.
I've totally failed to find a suitable email address or contact details for anyone technical behind BT Wi-Fi, hence my posting here.