I'm using a TP-LINK TL-WN781ND Wireless N card with an AR9285 chipset and an ath9k driver on Xubuntu 12.04.1 with Network manager.
'iwconfig wlan1' shows that it's using a bit-rate of 54 Mb/s. Is there a way (e.g. through an 'options' entry in '/etc/modprobe.d/ath9k.conf') of forcing it to use mode N? My router is doing 'Mode B/G/N Mixed'.