Two clocks. Do not mix them.
1. Lattice hosts
chrony (or ntpd) on every api, dhcpd, worker, and Postgres node. Offset < 500ms vs the writer. UTC. This is not a Lattice setting. See Clock.
2. DHCP clients (option 42)
On /subnets/{id}, NTP servers (opt 42) — comma-separated IPs, e.g. 10.0.0.10, 10.0.0.11. Admin, Save subnet.
Lattice puts those addresses on DHCPv4 option 42. You can still add option 42 as a raw DHCP option; the stored option wins if both exist.
API:
curl -s -X PATCH "http://127.0.0.1:8080/api/v1/subnets/${ID}" \
-H "authorization: Bearer $TOKEN" \
-H 'content-type: application/json' \
-d '{"ntp_servers":["10.0.0.10","10.0.0.11"]}'
Lattice does not speak NTP itself. It only tells clients where their NTP is.