@AlexisPHC said in Issues with Windows DHCP Server:

because we run them in HA mode

but there doesn’t seem to be another DHCP server present

My interpretation of these two statements sounds in opposition.

If you are running windows server in HA or failover mode, make sure that both dhcp servers have the dhcp boot options configured. If I remember right these settings are not copied over between the dhcp HA nodes. Understand this might have changed with later releases of dhcp server but with 2016 the pxe boot stuff needed to be set on each node individually.