It suports 40mhz, but not dual band. Read here: http://community.bt.com/t5/BB-Speed-Connection-Issues/Home-hub-3/td-p/136911
on 13-04-2013 17h35
The HH is dual band on 40mhz i believe...
No, its dual channel as in using channel 3 and 7 to deliver upto 300mbps across your home network. Dual band means operating on the 2.4ghz and 5ghz frequencies. The HH3b only operates on the 2.4ghz frequencies.
Some routers are described as simultaneous dual band , such as Netgear or Asus which means they operate on 2.4 & 5ghz at the same time while some are dual band but only operate on either frequency such as Draytek routers.
If you use a dual band router, you need to make sure your lappie and or pc's also have dual band wireless cards to get the best out of them.