Ok (sorry for the dumb question i edited out) I followed your steps and they works, but when I follow the guide (https://openwrt.org/docs/guide-user/network/wifi/routedap) and add the related steps to the config I end up with a wifi network where I cant connect. Can't connect also by cable 
I see no solution even if what i want to do is a comon thing..
is there anything else i can try? or this config is not supported by openwrt?
Do not replace the AP interface that you are logged in on, add a second one. Connect this second AP to the new "wifi" network.
Ok but even if I can connect back, I already tryed the guide https://openwrt.org/docs/guide-user/network/wifi/routedap and it doesent work so what should I next? Any idea? It seems to me that all the guides out there are like "configure your router as an access point" and there is nothing on "how to configure your access point to route traffic". So I should probably give up, use the netgear access point as a vanilla access point even if it is 2 times more powerful than my actual router..
Thanks..