No Internet through WLAN only, LAN works

Since yesterday, I am fighting with a problem: No Internet access thorough WLAN. The Turris Omina Rounter is working correctly with Ethernet, connection to the Internet is ok. But all clients connected through WLAN have no Internet. I didn’t change anything in the router settings, the only thing which happened was a short power failure in the night.

As I am not too familiar with all the Routers options, I would be happy to get some tips, which settengs could cause this problems.

FW: OpenWrt omnia 15.05 r47055 / LuCI 49c3edd5861fd032fa8379ceda525c27a908a114 branch (git-17.212.24321-49c3edd)

Thanks fro any help (also in Czech or German)