Wireless connection reverts to 802.11g

[Valcantor]

Recently aquired Vaio E Series SVE1511W1ESI with Atheros AR9485WB-EG network adapter.

I am connected to a BT HomeHub 2 802.11b/g/n. Connection at vaio switch on shows radio type as N but soon reverts to G, (neighbouring routers always show N). Using security WPA2 and AES, antennae set to full power and all drivers checked as current. Other laptop I use shows continuous N type when used at the same location as Vaio with line of sight to router. Have I a problem or is there something I have missed ?

[daempii]

Should there be a setting where you can see from the BT HomeHub to have this fixed?