Broadband wi fi problem

Alternatively you can split the 2.4ghz and 5ghz channels in the Homehub's settings. Eradicating the Apple/Homehub compatibility issues but retaining the benefits of the 5ghz band.

This is likely the best option, have 2 seperate SSIDs - "MyWiFi2.4Ghz" and "MyWifi5Ghz" or whatever you like then just have your iPad connect to whichever you receive a better service from, as it wont't have the other SSID stored it won't attempt to switch bands.

Here are instructions - http://bt.custhelp.com/app/answers/detail/a_id/56419/~/how-do-i-split-my-bt-hubs-ssid-(wireless-network-name)%3F

You shouldn't disable the 5Ghz band, 5Ghz is way less congested compared to 2.4Ghz and you should receive much better performance using it, if within range etc.

Probably just the start of the many problems with bt home hubs. If you can, get yourself a decent router and dont use the home hub. Iam yet to hear a good word said about bt internet and home hubs.

You clearly didn't look very far then as they've won multiple awards.

https://www.uswitch.com/broadband/awards/2008/wireless_broadband/

So ignoring the oh so typical BT bashing and continuing the advice, here's a guide on how to split the 5GHz and 2.4GHz into 2 different wireless networks. Make sure your iPad only connects to the 2.4GHz and other devices you can configure to use either network as you see fit. In theory the 5GHz has less contention with neighbours wifi or interference such as microwaves etc so should be faster, but in practice it's negligible unless you live in a very congested area with many wireless networks.

http://www.expertreviews.co.uk/networks/1404887/bt-smart-hub-settings-make-your-router-faster-and-less-annoying

The 5GHz range is fairly new so only very new routers will have it as an option, hence why you didn't see this issue on the old router.