Include Wifi-Repeater to network (receive 5Ghz and extend 2,4Ghz)

Hi guys,

I know little about this, but I tried to explain it in a picture.

This first one is my current situation, the second one I try to achieve:

Can you tell me which documentation I need to follow/apply to make it work?

Thanks and kind regards!

https://openwrt.org/docs/guide-user/network/wifi/relay_configuration