Connect different wlans


I'm a beginner openwrt user and I'm looking for suggestions about how to connect two different wifi lans together.

Currently I have a netgear router with dual band wlans, but I'd like to reuse this device only to give wifi access to a number of iot devices without changing anything, just moving the router in another room for coverage purposes.

I don't have possibilities to reach the netgear via ethernet cable.

From this new location, I should setup a wifi bridge - I think - that connects the old router to a new modem/router (fritzbox 7530).

Each device, the old netgear and the new fritzbox, have separate lans with different SSIDs and different networks, one is in and the other will probably be in 192.168.something.

How can I accomplish this configuration ?

What I have to look for ?