I have a Lenovo T420 with the following wireless card (as reported by `pciconf -lv`):

iwn0@pci0:3:0:0:	class=0x028000 card=0x13118086 chip=0x00858086 rev=0x34 hdr=0x00
    vendor     = 'Intel Corporation'
    device     = 'Centrino Advanced-N 6205 [Taylor Peak]'
    class      = network

Although I am able to connect to some networks, I have had severe problems connecting to my wireless router at home, which is an Asus RT-N66U, the "Dark Knight" router. I have been able to connect once or twice, but usually the connection fails for some reason. The relevant logs have a couple of repeating patterns:

Authentication timed out:
May 29 19:00:27 taipei wpa_supplicant[343]: wlan0: Trying to associate with 10:bf:48:53:10:2c (SSID='Goat Net 5GHz' freq=5805 MHz)
May 29 19:00:37 taipei wpa_supplicant[343]: wlan0: Authentication with 10:bf:48:53:10:2c timed out.
May 29 19:00:37 taipei wpa_supplicant[343]: wlan0: CTRL-EVENT-DISCONNECTED bssid=10:bf:48:53:10:2c reason=3 locally_generated=1

Associated, then immediately disconnected:
May 29 19:00:42 taipei wpa_supplicant[343]: wlan0: Trying to associate with 10:bf:48:53:10:2c (SSID='Goat Net 5GHz' freq=5805 MHz)
May 29 19:00:42 taipei wpa_supplicant[343]: wlan0: Associated with 10:bf:48:53:10:2c
May 29 19:00:42 taipei kernel: wlan0: link state changed to UP
May 29 19:00:43 taipei wpa_supplicant[343]: wlan0: CTRL-EVENT-DISCONNECTED bssid=10:bf:48:53:10:2c reason=0
May 29 19:00:43 taipei kernel: wlan0: link state changed to DOWN

I haven't had any luck getting this to work with the stock wpa_supplicant, which is at version 2.0.

However, I did install wpa_supplicant version 2.5 using pkg. It told me to add a line to rc.conf to use the installed wpa_supplicant instead of the base one. I rebooted, and my problems disappeared. I don't know why, but apparently the newer version fixed some problem I was having.

Can we upgrade the base version of wpa_supplicant from 2.0 to 2.5?

I don't know what is involved in this, but if somebody will point me in the right direction I may be able to help out.