I noticed that I did not have internet on wireless so I started to investigate, devices got DHCP lease when connected to wireless but did not respond to ping from router or from device to router.

After checking the config, disabled/enabled wlan interface, removed/added to bridge, set ip to wlan interface directly etc... nothing seemed to work so: /system reboot and it started working normaly.
After that I checked the log and I found:

06:23:38 system,error System rebooted because of kernel failure
06:23:38 system router rebooted

Router info:
uptime: 18m49s
version: 6.27
build-time: Feb/11/2015 13:24:13
free-memory: 101.7MiB
total-memory: 128.0MiB
cpu: MIPS 74Kc V4.12
cpu-count: 1
cpu-frequency: 600MHz
cpu-load: 2%
free-hdd-space: 108.9MiB
total-hdd-space: 128.0MiB
write-sect-since-reboot: 354
write-sect-total: 1592718
bad-blocks: 0%
architecture-name: mipsbe
board-name: RB951G-2HnD
platform: MikroTik