Is it possible to distribute IPs via dhcp and reserve them all at the same time?

Question

Computer networks

Essence: three pieces of iron that understand only dhcp. Router dsr500 with dhcp on board, distributing only three IPs with dynamics (conditionally - 10.10.10.1, 10.10.10.2, 10.10.10.3), all three IPs are reserved by macaddresses for pieces of iron.
Problem: they do not receive IP hardware.
If you add another IP to the dsr in the dhcp range (not associated with a reservation), then everything works as it should.
Question: what's the problem? in dsr500, in pieces of iron, or is this how dhcp works and is this normal?

Answer 1

Looks like an implementation glitch.

Answer 2

For issuing a range, specify the subnet? for example 10.10.10.1/30 or separate hosts?
Maybe you mess up in the mask (30 bits will not work, for example)?
If the hosts, then something strange, see if it is reserved somewhere else, listen to the traffic on L2, what the devices answer.