u/56Bot

My ISP modem doesn't let me choose DNS settings, so to make my Pi-Hole work I need to use its DHCP server. This would be easy if I had less Ethernet devices than ports on the modem. I don't.

My setup is physically constrained to the following :

ISP modem (Provides WiFi 7)
      - TV decoder
      - 4-port switch :
          - Pi-Hole
          - NAS server
          - Old semi-broken laptop running as a home server.
      - 1 free Ethernet cable for devices with no/poor WiFi (guests' older laptops for instance)

Important note : if I disable the modem's DHCP server the TV box stops working, because it needs the former's DNS settings (though I guess I could replicate those settings as fallback on the PiHole)

As for the switch, it has its own DHCP server and even a WiFi access point, though it dates from 2007 so it's painfully slow.

How should I set the DHCP servers so that I can protect the modem's WiFi network and all Ethernet devices with the PiHole, AND make the port forwarding work for my home server ?