I upgraded to BB from AA and tried to follow guest wlan instructions from here: http://wiki.openwrt.org/doc/recipes/guest-wlan
Connection to guest network failed - no IP address was assigned. Troubleshooting steps did not help.
What worked for me is replacing suggested
config 'interface' 'guest'
        option 'proto' 'static'
        option 'ipaddr' '10.0.0.1'
        option 'netmask' '255.255.255.0'
with(what I had before)
config interface 'guest'
        option type 'bridge'
        option _orig_ifname 'wlan0 wlan1'
        option _orig_bridge 'true'
        option proto 'static'
        option ipaddr '192.168.3.1'
        option netmask '255.255.255.0'
Router TP-Link WDR 4300 v 1.6
openwrt-ar71xx-generic-tl-wdr4300-v1-squashfs-factory.bin