Can't get pihole to work on br0 interface

Pointers for bridge setup halfway down in below posting of mine:

Ps. dhcpcd5 gets installed as "network manager" to deal with IP settings etc:

pi@noads:~ $ apt policy dhcpcd5
dhcpcd5:
  Installed: 1:6.11.5-1+rpt7
[..]

pi@noads:~ $ man dhcpcd5
[..]
DESCRIPTION
     dhcpcd is an implementation of the DHCP client specified in RFC
     2131.  dhcpcd gets the host information (IP address, routes, etc)
     from a DHCP server and configures the network interface of the
     machine on which it is running.  dhcpcd then runs the configuration
     script which writes DNS information to resolvconf(8), if available,
     otherwise directly to /etc/resolv.conf.  If the hostname is cur‐
     rently blank, (null) or localhost, or force_hostname is YES or TRUE
     or 1 then dhcpcd sets the hostname to the one supplied by the DHCP
     server.  dhcpcd then daemonises and waits for the lease renewal
     time to lapse.  It will then attempt to renew its lease and recon‐
     figure if the new lease changes when the lease beings to expire or
     the DHCP server sends message to renew early.

     If any interface reports a working carrier then dhcpcd will try and
     obtain a lease before forking to the background, otherwise it will
     fork right away.  This behaviour can be modified with the -b,
     --background and -w, --waitip options.
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