Thank you for the quick answer
Ok, I will watch out for any updates on this topic, thank you
By the way, wouldn't it work for you if you would insert all possible IP addresses? Like:
RnD confirmed that they will likely add this in the future development. For now, you should be able to add string address with help of CLI.
1.Go to CLI, log-in.
2. Type uci add_list dhcp.lan.dhcp_option="3,yourURLaddress"
3. Type uci commit
4. Type luci-reload
5. Type /etc/init.d/dnsmasq restart