If you bind to wan, make sure firewall is stopped or `12345` is allowed by firewall. Don't worry about the security of this port because this port has its own firewall rule.
Make sure you have bind to the correct LAN interfaces.
For example, if your use the same interface eth1 for WAN and LAN, write it as `wan_interface: eth1` and also in `lan_interface: eth1`. If the LAN interfaces you want to proxy are eth1 and docker0, write them both as `lan_interface: eth1,docker0`.
If does, stop the service process or change its listening port from 53 to others. Do not forget to modify `/etc/resolv.conf` to make DNS accessible (for example, with content `nameserver 223.5.5.5`, but do not use `nameserver 127.0.0.1`).