BT Home Hub 4/5 wifi less range than HH3?

I used to have a HH3 which was 2.4GHz only and got a good signal all through the house. Then it failed, and I was sent a replacement HH4 by BT. This was dual band. The 5GHz band was fine for the room the hub was in, but signal strength was pretty unusable elsewhere.

Worse, the 2.4GHz band did not give out a very good signal and upstairs my iPhone4s often dropped out of wifi, thereby using up my monthly data allowance for no good reason.

has anyone else seen this? Is the power output of the later hubs reduced - I can find no info on the web about specs like that?

5GHz due to physics does travel less distance and has a sharper cliff from good to bad, this is not just a HomeHub thing but other routers too.

On the 2.4GHz performance, everyone's experience seems to vary, but people seem to fare better by either replacing the HH completely, OR turning off its wireless and adding a dedicated wireless access point

I believe the HH4/5 have been upgraded to be neighbour-friendly which your HH3 was probably not.

I have the HH5 (b) and this has better range than the Netgear it replaced but neither can beat the Belkin that I had some time ago!

BT routers do broadcast two extra signals for their customers to use when away from home (if you have not switched it off) but I have not found this reducing the normal channel.