Upstream router: eth1: 192.168.20.0/24, eth2: 192.168.21.0/24
IP of Synology: 192.168.20.4
IP of Pihole: 192.168.20.4 (setup as "Use the same network as Docker Host")
IP within 192.168.20.0/24 is able to resolve IP via Pihole but not another subnet 192.168.21.0/24. I can see the DNS traffic from 192.168.21.0/24 on Synology with tcpdump but there is no return traffic from Pihole.
Does anyone know additional network setting is required for another subnet?