[Vicini]

I thought this was possible.
I only want up range 192.168.1.200 to 249 to use OpenDns
All others to use the router assigned dns

I already have this in the firewall which is working for all ip’s as it should.

iptables -t nat -A PREROUTING -i br0 -p udp --dport 53 -j DNAT --to $(nvram get lan_ipaddr)
iptables -t nat -A PREROUTING -i br0 -p tcp --dport 53 -j DNAT --to $(nvram get lan_ipaddr)

[egc]

Your router has to know which DNS server to handout to which client, that could be either by IP address (but not in this case as it is in the same subnet) or by MAC address.

What you can do is to default to OpenDNS and give static leases to clients you want to give another DNS server.
This is done with DNSMasq options see:
https://www.linksysinfo.org/index.php?threads/specific-gateway-dns-for-specific-clients.72461/

If it only is for wifi clients you can consider using a guest wifi where you specify an alternate DNS server (it is even possible to "attach" wired clients to the subnet of the guest wifi with VLAN's)

[Alozaros]

iptables -t nat -I PREROUTING -i br0 -s 192.168.1.102 -p udp --dport 53 -j DNAT --to 1.1.1.1
iptables -t nat -I PREROUTING -i br0 -s 192.168.1.102 -p tcp --dport 53 -j DNAT --to 1.1.1.1

presuming you use a br0 and replace those ip's with your ip's and dns required, you can use those lines with range, or mac too