I was able to get the Traffic Monitoring to work on my N66R running 380.65 Beta2.
After a factory reset and basic config, I formatted a 4 GIG thumbdrive with FAT32 and left the volume label blank.
Inserted the USB into the N66R, Tools, Other Settings, Traffic history location - Custom Location, Save History Location - select and create a folder on the USB. Apply then reboot the router.
After reboot - Tools, Other Settings, Save History Location - Select and choose the folder you created (Note: the USB was SDB at first and SDA after reboot) check Create or Reset data files, Apply.
Go to traffic history, daily and you should have something. If you have enough space on the USB you may want to create a swap file. If you have another USB drive make sure SDA does not "spin down."
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