Success with client mode!
Compared to default settings and wiki, I had to add wan interface and play with firewall.
The firewall is in rough shape(wide open) and needs more tuning, please, anybody with experience, comment.
Wan interface works pretty good, associates with AP by dhcp and assigned ip address is shown in ifconfig.
The rate in iwconfig is 0 Mb/s or 1Mb/s which is wrong, pinging AP return in 2-3ms, ping google from terminal ~40-45ms and the same from PC 45-50ms. Online tests show full 5Mb/s dowload speed.
The lan port is on a different subnet than wan and does assign ip address to PC by dhcp, that's nice.
There is still one annoyance. Someties traffic gets stuck or dropped for up to 1 minute, then suddenly comes back. I can't ping AP at that time, possibly that's wireless connection.
Next step it would be cool to set it up as a repeater.
Anyway, here are my settings.
root@OpenWrt:/etc/config# cat wireless
config wifi-device wlan0
option type mac80211
option channel 6
# REMOVE THIS LINE TO ENABLE WIFI:
option disabled 0
config wifi-iface
option device wlan0
option network wan
option mode sta
option ssid ToConnectTo
option encryption none
root@OpenWrt:/etc/config# cat network
config interface loopback
option ifname lo
option proto static
option ipaddr 127.0.0.1
option netmask 255.0.0.0
config interface lan
option ifname eth0
option type bridge
option proto static
option ipaddr 192.168.1.1
option netmask 255.255.255.0
config interface wan
# option ifname wlan0
option proto dhcp
root@OpenWrt:/etc/config# cat firewall
config defaults
option syn_flood 1
option input ACCEPT
option output ACCEPT
option forward ACCEPT
config zone
option name lan
option input ACCEPT
option output ACCEPT
option forward ACCEPT
config zone
option name wan
option input ACCEPT
option output ACCEPT
option forward ACCEPT
option masq 1
config forwarding
option src wan
option dest lan
# option mtu_fix 1
option proto tcp