Currently you have the 2.4Ghz and 5Ghz network named the same.
2.4Ghz is often much slower as it has lots more interference. However 2.4Ghz penetrates walls a lot better than 5Ghz.
If you are a distance away from the HomeHub, the 2.4Ghz will be a much stronger signal than the 5Ghz one. Your laptop will simply connect to the one with a stronger signal (the 2.4Ghz one). Despite the signal being stronger, chances are it will be slower. You would probably get a better speed using the 5Ghz signal, even if the reception was 2 bars weaker.
So yes, split the SSID, name one of them BTHomeHub-5xxxx2G
and one BTHomeHub-5xxxx-5G
Force the older laptop to connect to the 5G one.
Edited by ukhardy07 (Sun 18-Oct-15 13:56:05)