Thank you; it feels good to me that someone succeeded by following my suggestions. I also have run into the same problem of wifi disconnecting immediately after connecting during boot-up. This seems to happen consistently while using dhcpcd under netcfg/wpa_supplicant, but not while using dhcpcd directly or under the "network" package. Looking at the logfile, it seems that the carrier is lost, at which point the ra0 interface mysteriously goes down and dhcpcd doesn't reconnect. I have found that it is sufficient to "ifconfig ra0 up" or equivalent after booting, and then dhcpcd reconnects and stays connected just fine. For this purpose, I have put the following admittedly cryptic lines into my /etc/rc.local:
$this->bbcode_second_pass_code('', '# Re-up ra0 in case it dropped for no good reason.
[[ -n "$(ps -C dhcpcd -o pid=)" && $(cat /sys/class/net/ra0/operstate) != up ]] && ip link set ra0 up >/dev/null 2>&1 || true
')
My earlier suggestion about using the "-K" flag of dhcpcd doesn't seem to be sufficient. I hope someone can find a better solution.