I only have two devices connecting via N with DWA-652 cards. With all versions of the firmware, I have consistantly had problems trying to run mixed G/N on the DIR-655 so all my G devices connect via my old G router. My connection rate consistantly shows 300Mbps on the laptops, and the wireless status on the router consistantly shows 270Mbps in the Rate column when the devices are active.
Here are the settings from my DIR-655 in case anyone wants to try the same settings:
Hardware Version: A3
Firmware Version : 1.20, 2008/07/09
Connection Up Time: 45 Day 16 Hour 27 Min 20 Sec
Wireless Settings:
N-only, Channel 11, Transmission rate Best (automatic), auto 20/40 MHz, WPA-Personal, WPA2 Only, AES.
Advanced Wireless:
Power High, Beacon 100, WMM Enable, Short GI, Extra wireless Protection
Regards,
BSPVettte