Post again the same.
Hi all just to share part of the solution and what I've found:
A - Internet provider router (wifi turned off)
B - GL.iNet GL-B1300 with OpenWrt 21.02-r4 connected via cable to the internet provider's router
C - Netgear Extender EX6150v2 with OpenWrt 21.02-r4 connected via cable to B
The ip's actually are A) 192.168.1.1 B) 192.168.2.1 C) 192.168.2.10
(A) is VodafoneStation: if you leave Vodafone DNS seems that Openwrt Dns config is somehow bypassed. I changed (A) dns (internet -> dns) to 8.8.8.8 and immediatly started to resolve from (C) with Openwrt configured DNS (Cisco family shield in LAN section).
Then I had to do on my laptop
sudo systemd-resolve --flush-caches
and test again from (B) and now (B) shows Cloudflare family dns (configured in WAN-Advanced).
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