Searching for "ar5213" in the misc@ mailing list archives, it looks like this chipset may work with 802.11b (up to 11Mbit/s) WiFi networks, but
not 802.11g (up to 54Mbit/s). See the
mode option in the
ifconfig(8) man page to force the NIC to use 802.11b ("mode 11b") -- of course, your Access Point must have 802.11b capability configured.