Hi.
You can filter your traffic at the DNS query level.
For example, using SSH commands or in the CLI menu from WebUI:
For Blacklist
uci add_list dhcp.@dnsmasq[0].server="/example.com/"
uci add_list dhcp.@dnsmasq[0].server="/example.net/"
uci commit dhcp
/etc/init.d/dnsmasq restart
For Whitelist
uci add_list dhcp.@dnsmasq[0].server="/example.com/#"
uci add_list dhcp.@dnsmasq[0].server="/example.net /#"
uci commit dhcp
/etc/init.d/dnsmasq restart
You can cancel the filter with the following command
uci del_list dhcp.@dnsmasq[0].server="/site.com/"
Best regards.