I was trying Kea DHCP yesterday, however my device complaind about internet access
I then notices that while I edited the DNS, NTP, it kept rolling back to settings that I didnt want to, for example interface IP as DNS while I need them manually configured.
Yes that's a very confusing thing, happened to me too:
You have to disable 'Auto collect option data' in the subnet page (tip in another thread here, I would have never thought of that)