Unable to connect to client Wi-Fi network

I am trying to connect my OpenWrt (18.06) router to another Wi-Fi network (OpenWrt 21.02), but I am unable to.

Both the routers are on different subnets: 192.168.1.x and 192.168.2.x.

The wireless overview page show this

While joining the scan page show good signal strength

Why the signal strength is zero? What could be the issue?

Signal strength when trying to join the network

What is mode of second router (WiFi-client)? What channel is used after establishing connection?