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I have pihole running inside a docker on a raspberry pi.
I set my router DNS as the raspberry pi IP address.
It seems like everything is working properly, but on the pi hole dashboard, under Top Clients, I can see only my router with above 100,000 requests.
It seems like the pi hole listing all of the devices traffic under the router traffic and not under each device.
Those are my settings:
DNS configuration in pi hole
Note that Pi-hole is not involved in routing at all.
It just listens for DNS requests.
Your observation would suggest that you've configured your router to use Pi-hole as its only upstream (commonly, a WAN/Internet kind of option), i.e. your router aggregates DNS traffic from your network clients and forwards that to Pi-hole.
That is a valid configuration, but you won't be able to attribute DNS requests to individual clients (as you've observed).
For that, it would be required that your router would tell its clients to use Pi-hole for DNS instead instead of the router itself (commonly, that is a LAN/DHCP kind of option).
You'd have to consult your router's documentation for details on its DNS configuration options.